Patent Publication Number: US-2022232823-A1

Title: Ex vivo organ care system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/509,520 filed Oct. 25, 2021; which is a continuation of U.S. patent application Ser. No. 16/130,255 filed Sep. 13, 2018, issued as U.S. Pat. No. 11,154,050; which is a continuation of U.S. patent application Ser. No. 14/728,771 filed Jun. 2, 2015, issued as U.S. Pat. No. 10,076,112; which claims the benefit under 35 U.S.C. § 119(e) of provisional application U.S. Ser. No. 62/006,871, filed Jun. 2, 2014, entitled, “EX VIVO ORGAN CARE SYSTEM”, and U.S. Ser. No. 62/006,878, filed Jun. 2, 2014, entitled, “EX VIVO ORGAN CARE SYSTEM.” The entire contents of each of the above is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention generally relates to systems, methods, and devices for ex vivo organ care. More particularly, in various embodiments, the invention relates to caring for an organ ex vivo at physiologic or near-physiologic conditions. 
     BACKGROUND 
     Current organ preservation techniques typically involve hypothermic storage of the organ packed in ice along with a chemical perfusate solution. In the case of a liver transplant, tissue damage resulting from ischemia can occur when hypothermic techniques are used to preserve the liver ex vivo. The severity of these injuries can increase as a function of the length of time the organ is maintained ex-vivo. For example, continuing the liver example, typically it may be maintained ex-vivo for about seven hours before it becomes unusable for transplantation. This relatively brief time period limits the number of recipients who can be reached from a given donor site, thereby restricting the recipient pool for a harvested liver. Even within this time limit, the liver may nevertheless be significantly damaged. A significant issue is that there may not be any visible indication of the damage. Because of this, less-than-optimal organs may be transplanted, resulting in post-transplant organ dysfunction or other injuries. Thus, it is desirable to develop techniques that can extend the time during which an organ such a liver can be preserved in a healthy state ex-vivo and enable assessment capabilities. Such techniques would reduce the risk of transplantation failure and enlarge potential donor and recipient pools. 
     SUMMARY 
     The below summary is exemplary only, and not limiting. Other embodiments of the disclosed subject matter are possible. 
     Embodiments of the disclosed subject matter can provide techniques relating to portable ex vivo organ care, such as ex vivo liver organ care. In some embodiments, the liver care system can maintain the liver at, or near, normal physiological conditions. To this end, the system can circulate an oxygenated, nutrient enriched perfusion fluid to the liver at or near physiological temperature, pressure, and flow rate. In some embodiments, the system employs a blood product-based perfusion fluid to more accurately mimic normal physiologic conditions. In other embodiments, the system uses a synthetic blood substitute solution, while in still other embodiments, the solution can contain a blood product in combination with a blood substitute product. 
     Some embodiments of the disclosed subject matter relate to a method for using lactate and liver enzyme measurements to evaluate the: i) overall perfusion status of an isolated liver, ii) metabolic status of an isolated liver, and/or iii) the overall vascular patency of an isolated donor liver. This aspect of the disclosed subject matter is based on the ability of liver cells to produce/generate lactate when they are starved for oxygen and metabolize/utilize lactate for energy production when they are well perfused with oxygen. 
     Some embodiments of the organ care system can include a module that has a chassis, and an organ chamber assembly that is mounted to the chassis and is adapted to contain a liver during perfusion. The organ care system can include a fluid conduit with a first interface for connecting to a hepatic artery of the liver, a second interface for connecting to the portal vein, a third interface for connecting to the inferior vena cava and a fourth interface to connect to the bile duct. The organ care system can include a lactate sensor for sensing lactate in the fluid being provided to and/or flowing from the liver. The organ care system can also include sensors for measuring the pressures and flows of the hepatic artery, portal vein, and/or inferior vena cava. 
     Some embodiments can relate to a method of determining liver perfusion status. For example, a method for evaluating liver perfusion status can include the steps of placing a liver in a protective chamber of an organ care system, pumping a perfusion fluid into the liver, providing a flow of the perfusion fluid away from the liver, measuring the lactate value of the fluid leading away from the liver, measuring the amount of bile produced by the liver, and evaluating the status of the liver using the measured lactate values, oxygen saturation level, and/or the quantity and quality of bile produced. 
     Some embodiments can relate to a method for providing a physiologic rate of flow and a physiologic pressure for both the hepatic artery and for the portal vein. In some embodiments the flow is sourced by a single pump. In particular, the system can include a mechanism for the user to manually divide a single source of perfusate to the hepatic artery and portal vein, and to adjust the division for physiologic flow rates and pressures. In other embodiments the system automatically divides the single source of perfusate flow to the hepatic artery and portal vein to result in physiologic pressures and rates of flow using, for example, an automatic control algorithm. 
     Some embodiments of the organ care system can include a nutritional subsystem that infuses the perfusion fluid with a supply of maintenance solutions as the perfusion fluid flows through the system, and in some embodiments, while it is in the reservoir. According to one feature, the maintenance solutions include nutrients. According to another feature, the maintenance solutions include a supply of therapeutics and/or additives to support extended preservation (e.g., vasodilators, heparin, bile salts, etc.) for reducing ischemia and/or other reperfusion related injuries to the liver. 
     In some embodiments, the perfusion fluid includes blood removed from the donor through a process of exsanguination during harvesting of the liver. Initially, the blood from the donor is loaded into the reservoir and the cannulation locations in the organ chamber assembly are bypassed with a bypass conduit to enable normal mode flow of perfusion fluid through the system without a liver being present, aka “priming tube”. Prior to cannulating the harvested liver, the system can be primed by circulating the exsanguinated donor blood through the system to warm, oxygenate and/or filter it. Nutrients, preservatives, and/or other therapeutics may also be provided during priming via the infusion pump of the nutritional subsystem. During priming, various parameters may also be initialized and calibrated via the operator interface. Once primed and running appropriately, the pump flow can be reduced or cycled off, the bypass conduit can be removed from the organ chamber assembly, and the liver can be cannulated into the organ chamber assembly. The pump flow can be restored or increased, as the case may be. 
     In some embodiments, the system can include a plurality of compliance chambers. The compliance chambers are effectively small inline fluid accumulators with flexible, resilient walls for simulating the human body&#39;s vascular compliance. As such, they can aid the system in more accurately mimicking blood flow in the human body, for example, by filtering/reducing fluid pressure spikes due, for example, to flow rate changes. In one configuration, compliance chambers are located in the perfusate path to the portal vein and on the output of the perfusion fluid pump. According to one embodiment, a compliance chamber is located next to a clamp used for regulating pressure to effect physiologic hepatic artery and portal vein flows. 
     In some embodiments, the organ chamber assembly includes a pad or a sac assembly sized and shaped for interfitting within a bottom of the housing. Preferably, the pad assembly includes a pad formed from a material resilient enough to cushion the organ from mechanical vibrations and shocks during transport. In the case of the organ chamber assembly being configured to receive a liver, according to one feature, the pad of the invention includes a mechanism to conform the pad to differently sized and shaped livers so as to constrain them from the effects of shock and vibration encountered during transport. 
     Some embodiments of the organ care system are divided into a multiple use module and a single use module. The single use module can be sized and shaped for interlocking with the portable chassis of the multiple use module for electrical, mechanical, gas and fluid interoperation with the multiple use module. According to one embodiment, the multiple and single use modules can communicate with each other via an optical interface, which comes into optical alignment automatically upon the single use disposable module being installed into the portable multiple use module. According to another feature, the portable multiple use module can provide power to the single use disposable module via spring loaded connections, which also automatically connect upon the single use disposable module being installed into the portable multiple use module. According to one feature, the optical interface and spring loaded connections can ensure that connection between the single and multiple modules is not lost due to jostling, for example, during transport over rough terrain. 
     In some embodiments, the disposable single-use module includes a plurality of ports for sampling fluids from the perfusate paths. The ports can be interlocked such that sampling fluid from a first of the plurality of ports prohibits simultaneously sampling fluids from a second port of the plurality. This safety feature reduces the likelihood of mixing fluid samples and inadvertently opening the ports. In one embodiment, the single use module includes ports for sampling from one or more of the hepatic artery, portal vein, and/or IVC interfaces. 
     Some embodiments of the disclosed subject matter are directed at a method of providing therapy to a liver. Exemplary methods can include placing a liver in a protective chamber of a portable organ care system, pumping a perfusion fluid into the liver via a hepatic artery and portal vein, providing a flow of the perfusion fluid away from the liver via the vena cava, operating a flow control to alter a flow of the perfusion fluid such that the perfusion fluid is pumped into the liver via a hepatic artery and portal vein and flows away from the liver via a vena cava, and administering a therapeutic treatment to the liver. The treatments can include, for example, administering one or more of immunosuppressive treatment, chemotherapy, gene therapy and irradiation therapy to the liver. Other treatments may include surgical applications including split transplant and cancer resection. 
     In some embodiments, the disclosed subject matter can include a perfusion circuit for perfusing a liver ex-vivo, the perfusion circuit including a single pump for providing pulsatile fluid flow of a perfusion fluid through the circuit; a gas exchanger; a divider configured to divide the perfusion fluid flow into a first branch and a second branch; wherein the first branch is configured to provide a first portion of the perfusion fluid to a hepatic artery of the liver at a high pressure and low flow rate, wherein the first branch is in fluid pressure communication with the pump; wherein the second branch is configured to provide the remainder of the perfusion fluid to a portal vein of the liver at a relatively low pressure and high flow rate, wherein the second branch is in fluid pressure communication with the pump; the second branch further comprising a clamp located between the divider and the liver for selectively controlling the flow of perfusion fluid to the portal vein; the second branch further comprising a compliance chamber between the divider and the liver configured to reduce the pulsatile flow characteristics of the perfusion fluid from the pump to the portal vein; wherein the pump is configured to communicate fluid pressure through the first and second branches to the liver; a drain configured to receive perfusion fluid from an uncannulated inferior vena cava of the liver; and a reservoir positioned entirely below the liver and located between drain and the pump, configured to receive the perfusion fluid from the drain and store a volume of fluid. Other embodiments are possible. 
     In some embodiments, the disclosed subject matter can include a solution pump including a stepper motor in communication with a threaded rod; a carriage that is connected to the rod and configured to move along a linear axis as the rod rotates, the carriage being configured to compress a plunger of a syringe when moved in a first direction and being configured to retract the plunger of the syringe when moved in a second direction; a clamp configured to connect to the plunger; a connection assembly including a port configured to couple to a tip of the syringe; a first one way valve configured to allow fluid to flow into the syringe through the port as the syringe is retracted; a second one way valve configured to allow fluid to flow away from the syringe through the port as the syringe is compressed; a pressure sensor coupled to the connection assembly for determining a pressure of the fluid within the connection assembly; a controller configured to control operation of the stepper motor; and a sensor configured to determine when the syringe is fully retracted. Other embodiments are possible. 
     In some embodiments, the disclosed subject matter can include a method including rotating a rod to cause a carriage connected to the rod to move along a linear axis of the rod, compressing a plunger of a syringe as the carriage moves in a first direction along the linear axis, delivering fluid from the syringe into a port of a connection assembly and through a first one-way valve as the plunger is compressed, retracting a plunger of a syringe as the carriage moves in a second direction along the linear axis, delivering fluid to the syringe through a second one-way valve, and through the port of the connection assembly as the plunger is retracted, sensing a pressure of fluid in the connection assembly, and sensing a location of the plunger when the syringe is retracted. Other embodiments are possible. 
     In some embodiments, the disclosed subject matter can include an ex-vivo perfusion liquid for machine perfusion of donor livers comprising an energy-rich component, a bile salt, an electrolyte, and a buffering component. The liquid can include a blood product. The energy-rich component can be one or more compounds selected from the group consisting of a carbohydrate, pyruvate, flavin adenine dinucleotide (FAD), β-nicotinamide adenine dinucleotide (NAD), β-nicotinamide adenine dinucleotide phosphate (NADPH), a phosphate derivative of nucleoside, a coenzyme, and metabolite and precursor thereof. The liquid further includes one or more components selected from the group consisting of an anti-clotting agent, a lipid, cholesterol, a fatty acid, oxygen, an amino acid, a hormone, a vitamin, and a steroid. The perfusion solution is essentially free of carbon dioxide. Other embodiments are possible. 
     These and other embodiments of the disclosed subject matter will be more fully understood after a review of the following figures, and detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The following drawings are intended show non-limiting examples of the disclosed subject matter. Other embodiments are possible. 
         FIG. 1  is an exemplary diagram of a liver. 
         FIG. 2  is a line drawing of an exemplary single use module. 
         FIGS. 3A-3I  show various views of an exemplary organ care system and components thereof. 
         FIG. 4  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIG. 5  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIGS. 6A-6E  show an exemplary pump configuration that can be used within an embodiment of the organ care system. 
         FIGS. 7A-7Q  show an exemplary solution infusion pump that can be used within an embodiment of the organ care system. 
         FIG. 8  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIG. 9  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIG. 10  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIG. 11  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIGS. 12A-12G  show exemplary graphical user interfaces that can be used within an embodiment of the organ care system. 
         FIG. 12H  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIGS. 13A-13R  show exemplary embodiments of a single use module and components thereof that can be used in an embodiment of the organ care system. 
         FIGS. 14A-14S  show exemplary embodiments of an organ chamber and components thereof that can be used in an embodiment of the organ care system. 
         FIGS. 15A-15D  show an exemplary embodiment of a support structure that can be used in an embodiment of the organ care system. 
         FIGS. 16A-16J  show an exemplary pad and components thereof and a flexible material support surface that can be used in embodiments of the organ care system. 
         FIG. 17  shows an exemplary system that can be used within an embodiment of the organ care system. 
         FIGS. 18A-18G  show an exemplary heater assembly and components thereof that can be used within an embodiment of the organ care system. 
         FIGS. 19A-19C  show an exemplary sensor system that can be used within an embodiment of the organ care system. 
         FIGS. 20A-20C  show an exemplary system that can be used within an embodiment of the organ care system. 
         FIGS. 21A-21K  show exemplary hepatic artery cannulas that can be used within an embodiment of the organ care system. 
         FIGS. 22A-22G  show exemplary portal vein cannulas that can be used within an embodiment of the organ care system. 
         FIGS. 23A-23N  show an exemplary connector that can be used within an embodiment of the organ care system. 
         FIGS. 24A-24L  show an exemplary connector that can be used within an embodiment of the organ care system. 
         FIGS. 25A-25D  show exemplary clamps that can be used within an embodiment of the organ care system. 
         FIGS. 26-27  show exemplary processes that can be used in embodiments of an organ care system. 
         FIG. 28  shows exemplary test results from an embodiment of an organ care system. 
         FIG. 29  shows an exemplary process that can be used in embodiments of an organ care system. 
         FIG. 30  shows exemplary systems that can be used within an embodiment of the organ care system. 
         FIG. 31  shows the hepatic artery flow (HAF) trend throughout the course of 8 hours preservation on OCS. 
         FIG. 32  shows the portal vein flow (PVF) trend throughout the course of 8 hours preservation on OCS. 
         FIG. 33  shows a graphical depiction of hepatic artery pressure versus portal vein pressure throughout the 8-hour OCS-liver perfusion. 
         FIG. 34  is a graphical depiction of arterial lactate levels over the 8-hour OCS liver perfusion. 
         FIG. 35  is a graphical depiction of total bile production over the 8-hour OCS liver perfusion. 
         FIG. 36  is a graphical depiction of AST level over the 8-hour OCS liver perfusion. 
         FIG. 37  is a graphical depiction of ACT level over the 8-hour OCS liver perfusion. 
         FIG. 38  is a graphical depiction of oncotic pressure throughout the course of 8 hours preservation on OCS. 
         FIG. 39  is a graphical depiction of bicarb levels over the 8-hour OCS liver perfusion. 
         FIG. 40  is a depiction of the detected pH levels throughout the course of 8 hours preservation on OCS. 
         FIG. 41  shows images of tissues taken from samples in Phase I, Group A. 
         FIG. 42  depicts Hepatic Artery Flow of a 12 hr OCS Liver Perfusion. 
         FIG. 43  depicts Portal Vein Flow of a 12 hr OCS Liver Perfusion. 
         FIG. 44  depicts Hepatic Artery Pressure vs. Portal Vein Pressure in a 12 hr OCS-Liver Perfusion. 
         FIG. 45  depicts Arterial Lactate in a 12 hr OCS-Liver Perfusion. 
         FIG. 46  depicts Bile Production in a 12 hr OCS-Liver Perfusion. 
         FIG. 47  depicts AST Level of a 12 hr OCS-Liver Perfusion. 
         FIG. 48  depicts ACT Levels in a 12 hr OCS-Liver Perfusion. 
         FIG. 49  depicts Hepatic Artery Flow on a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 50  depicts Portal Vein Flow on a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 51  depicts Hepatic Artery Pressure vs. Portal Vein Pressure in a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 52  depicts Arterial Lactate on a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 53  depicts bile production of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 54  depicts a AST Level of simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 55  depicts ACT Levels of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 56  depicts oncotic pressure of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 57  depicts the Bicarb Level of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 58  depicts pH Levels of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
         FIG. 59  shows the histological examination of Parenchymal tissue and Bile duct tissue. 
         FIG. 60  shows the histological examination of Parenchymal tissue and Bile duct tissue. 
         FIG. 61  is a diagram illustrating locations of samples from a liver of a pig. 
         FIG. 62  illustrates the Hepatic Artery Pressure (HAP) trend over the course of 24 hours perfusion on the OCS. 
         FIG. 63  illustrates the Portal Vein Pressure in an OCS-Liver Preservation arm vs the control Cold preservation arm. 
         FIG. 64  illustrates a Hepatic Artery Flow in a OCS-Liver Preservation arm vs. control Cold preservation arm. 
         FIG. 65  illustrates a Portal Vein Flow in an OCS-Liver Preservation arm vs. control Cold preservation arm. 
         FIG. 66  depicts Arterial Lactate in an OCS-Liver Preservation arm vs. a control Cold preservation arm. 
         FIG. 67  illustrates an AST Level OCS-Liver Preservation arm vs. control Cold Preservation arm. 
         FIG. 68  illustrates an ALT Level OCS-Liver Preservation arm vs. control Cold preservation arm. 
         FIG. 69  depicts a GGT Level of an OCS-Liver Preservation arm vs. control Cold preservation arm. 
         FIG. 70  depicts a PH level of an OCS-Liver Preservation arm vs. a control Cold preservation arm. 
         FIG. 71  depicts a HCO3 level in an OCS-Liver Preservation arm vs. a Control Cold preservation arm. 
         FIG. 72  depicts a bile production OCS-Liver Preservation arm vs. control Cold preservation arm. 
         FIG. 72  demonstrates that both arms maintained bile production rate of &gt;10 ml/hr. 
     
    
    
     DETAILED DESCRIPTION 
     While the following description uses section headings, these are included only as a convenience to the reader. The section headings are not intended to be limiting or impose any restriction on the subject matter herein. For example, components described in one section of the description can be included in other sections additionally or alternatively. The embodiments disclosed herein are exemplary only and it is within the scope of the present disclosure that the disclosed embodiments and various features may be interchanged with one another. 
     I. Introduction 
     A. General Summary 
     Embodiments of the disclosed subject matter can provide techniques for maintaining a liver ex vivo, such as during a transplant procedure. The system can maintain a liver in conditions mimicking the human body. For example, the system can supply a blood substitute to an ex vivo liver in a manner that simulates the blood flow provided by the body. More specifically, the system can provide a flow of blood substitute to a hepatic artery and portal vein of a liver having flow and pressure characteristics similar to the human body. In some embodiments, the desired flows can be achieved using a pumping system that employs a single pump. The system can also warm the blood substitute to a normothermic temperature that simulates the human body and can provide nutrients to the blood substitute to maintain the liver and to promote the normal generation of bile by the liver. By performing these techniques, the length of time that a liver can be maintained outside the body can be extended, thereby making the geographical distance between donors and recipients less important than it previously was. Also, some of the embodiments disclosed herein that are used to maintain the liver ex vivo can also be used to assess the condition of the liver pre-transplant. In some embodiments, the techniques described herein can also be used to treat an injured and/or diseased liver ex vivo using treatments that would otherwise be harmful to the body if performed in vivo. Other embodiments are within the scope of the disclosed subject matter. 
     While the disclosure herein focuses on embodiments that are intended to maintain or treat a liver, the disclosure is not limited as such. For example, techniques described herein can also be used, or can be adapted for use with other organs such as lungs, a heart, intestines, a pancreas, a kidney, a spleen, a bladder, a gallbladder, a stomach, skin, and a brain. 
     II. Liver Compared with Other Organs 
     While the liver is one of many organs in the human body, the liver can present challenges during ex vivo maintenance and transport that do not exist with other organs such as the heart and lungs. Some exemplary differences and considerations are described next. 
     A. Liver Uses Two Perfusate Inflow Supplies 
     Importantly, the liver uses two unique input paths for perfusate as compared with only one for other organs. Hepatic circulation is unique as featured by its dual vascular blood supply, each having different flow characteristics. Referring to  FIG. 1 , which is an exemplary conceptual drawing of a liver  100 , the liver uses two blood supplies, the portal vein  10  and the hepatic artery  12 . In particular, the hepatic artery delivers blood to the liver having high pressure, pulsatile flow, but of relatively low flow rate. Hepatic blood flow typically accounts for about one-third of the total liver blood flow. The portal vein delivers blood to the liver having a low pressure and minimal pulsatility at a higher flow rate. Portal vein flow typically accounts for about two-thirds of the total blood flow to the liver. 
     The dual blood supply expected by the liver can present challenges when one tries to artificially supply physiologic blood flow thereto when the organ is in an ex vivo system. While the challenges can be difficult when using a dual-pump design, they can be intensified when using a single-pump design. Some embodiments of the subject matter disclosed herein can address these challenges. 
     B. Assisted Drainage of Blood 
     In vivo, the liver is positioned beneath the diaphragm. Due to this positioning, liver blood flow and venous drainage via the inferior vena cava  14  is typically enhanced by diaphragmatic contraction as a result of pressure exerted on the liver. When the diaphragm moves in tandem with the lungs as air is drawn in and expelled by the lungs, the movement of the diaphragm can act on the liver by applying pressure to the organ, thereby pushing blood out of the tissue. It is desirable to mimic this phenomenon in an ex-vivo liver to help encourage blood flow out of the liver and prevent blood buildup in the organ. 
     C. Oncotic Pressure 
     To minimize edema formation in an ex vivo liver, the perfusate should have high oncotic pressure, for example, dextran, 25% albumin, and/or fresh frozen plasma. In some embodiments, oncotic pressure of the circulating perfusate is maintained between 5-35 mmHg, and more specifically between 15-25 mmHg. Non-limiting examples of possible oncotic pressures are 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 mmHg, or any ranges bounded by the values noted here. 
     D. Metabolism and CO 2  Levels 
     The liver is a metabolic hub in the body and is in a constant state of metabolism. Most compounds absorbed by the intestine first pass through the liver, which is thus able to regulate the level of many metabolites in the blood. For example, the conversion of sugars into fat and other energy stores (e.g., gluconeogenesis and glycolysis) results in production of CO 2 . The liver consumes about 20% of the total body oxygen. As a result, the liver produces higher levels of CO 2  than most other organs. In vivo, the organ is able to self-regulate to remove excess carbon dioxide from the organ. However, for an ex-vivo organ, it can be desirable to remove excess carbon dioxide from the organ to maintain physiologic levels of oxygen and carbon dioxide and thus pH. The system described in this application can facilitate establishment of blood chemistry equilibrium suitable for organ preservation ex vivo. 
     E. Bile Production 
     The liver is an excrement producing organ. The excrement, bile, is usually produced and excreted by the organ in vivo. Bile is produced in the liver by hepatocytes. In vivo, the liver utilizes bile salts to create bile, and bile salts are recycled through the enterohepatic circulation system back to the liver to be reused. The bile salts in turn stimulate the hepatocytes to produce more bile. Ex vivo, bile salts are not recycled back to the liver. As a result, it can be desirable to supplement perfusate with bile salts to aid the organ in producing bile. Additionally, in some instances, the bile produced by the liver can provide an indication (e.g., quantity, color and consistency) of the suitability of the organ for transplant. 
     F. Supporting a Liver 
     The liver is the largest solid organ in the body, but it is delicate and fragile. In the body, it is protected by the rib cage and other organs. Unlike many other organs, the liver does not include protective elements and is not defined by a rigid structure. Therefore, when the liver is removed from the body and maintained ex-vivo, it should be treated more delicately than other organs. For example, it can be desirable to provide proper support for the liver, place the liver on a low friction surface, and/or cover the organ with a wrap to protect the organ from damage during transport and while being maintained ex vivo. 
     G. Perfusate 
     Given the liver&#39;s wide range of vital functions when compared with other organs (e.g., detoxification, protein synthesis, glycogen storage, and production of biochemicals necessary for digestion), the perfusion fluid used in the organ care system described herein can be specially designed to maintain the liver in close to its physiological state to maintain its regular functions. For instance, because the liver is in a constant state of metabolism consuming energy, the oxygen content in the perfusion fluid can be maintained at close to or more than the physiological level to meet its high demand as a metabolic warehouse. Similarly, the perfusion fluid can also be designed to include sufficient concentration of energy-rich components, such as carbohydrates and electrolytes, to provide the liver with an energy source to carry out its functions. 
     The flow rate of the perfusion fluid can be also properly adjusted to ensure that oxygen and nutrients are delivered to an ex vivo liver at a suitable rate. Furthermore, the carbon dioxide content in the perfusion liquid can be lower than the level in physiological state, thus further driving the equilibrium of the liver&#39;s biological reactions to metabolism and oxidation. In some embodiments, the perfusion fluid used herein does not contain significant amount of carbon dioxide or is free from all carbon dioxide. In some embodiments, the perfusion fluid used herein also contains sufficient amount of bile salt to sustain the need of the liver to produce bile. Thus, the perfusion fluid for the organ care system described herein can be designed to maintain the liver&#39;s regular cellular functions to maintain the liver in a viable state. 
     III. Description of Exemplary System Components 
     A. General Architecture 
       FIG. 3  shows an exemplary organ care system  600  that can be used to preserve an organ such as a liver when the organ is ex vivo during, for example, a transplant operation or medical procedure. At a general level, the organ care system  600  is configured to provide conditions to an ex vivo organ that mimic the conditions the organ experiences when in vivo. For example, in the case of a liver, the organ care system  600  can provide a perfusate flow to the organ in a manner that mimics blood flow in a human body (e.g., flow, pressure, and temperature) and provide similar environmental characteristics (e.g., temperature). 
     In some embodiments, the organ care system  600  can be divided into two parts: a disposable single-use portion (e.g.,  634 ) and a non-disposable multiple-use portion (e.g.,  650 ) (also referred to herein as a single-use module and a multiple-use module). As the names imply, the single-use portion can be replaced after a liver is transported and the multiple-use portion can be reused. At a general level, though not required, the single-use portion includes those portions of the system that come into direct contact with biological material whereas the multiple-use portion includes those components that do not come into contact with biological material. In some embodiments, all of the components in the single-use portion are sterilized before use, whereas the components in the multiple-use portion are not. Each of the portions are described in detail below. This configuration allows a method of operation where, after use, the entire single-use module  634  can be discarded and replaced with a new single-use module. This can allow the system  600  to be available for use again after a short turnaround time. 
     Typically the single and multiple use portions can be configured to be removably connected to one another via a mechanical interface. Additionally, the single and multiple use portions can include mechanical, gas, optical, and/or electrical connections to allow the two portions to interact with one another. In some embodiments, the connections between the portions are designed to be connected/unconnected from one another in a modular fashion. 
     The disposable module  634  and the multiple use module  650  can be constructed at least in part of material that is durable yet light-weight such as polycarbonate plastic, carbon fiber epoxy composites, polycarbonate ABS-plastic blend, glass reinforced nylon, acetal, straight ABS, aluminum, and/or magnesium. In some embodiments, the weight of the entire system  600 , is less than 100 pounds, including the multiple use module, organ, batteries, gas tank, and priming, nutritional, preservative and perfusion fluids, and less than about 50 pounds, excluding such items. In some embodiments, the weight of the single use module  634  is less than 12 pounds, excluding any solutions. In some embodiments, the multiple use module, excluding all fluids, batteries, and gas supply, weighs less than 50 pounds. 
     With the cover removed and the front panel open, an operator can have easy access to many of the components of the disposable  634  and multiple use 650 modules. For example, the operator can access the various components of the single and multiple use modules and can install and/or remove the single use module from to/from the multiple use module. 
     While certain components are described herein as being in the single-use portion or the multiple-use portion of the system  600 , this is exemplary only. That is, components identified herein as being located in the single-use portion can also be located in the multiple-use portion and vice-versa. 
     B. Exemplary Multiple Use Module 
     Referring to  FIGS. 3A-3I , the multiple use module can include several components including a housing, a cart, a battery, a gas supply, at least part of a perfusion fluid pump, an infusion pump, and a control system. 
     1. Cart/Housing 
     Referring to  FIGS. 3A-3I , an exemplary embodiment of the organ care system is shown as organ care system  600  can include a housing  602  and a cart  604 . The cart  604  can include a platform and wheels for transporting the system  600  from place to place. A latch  603  can secure the housing  602  to the cart  604 . To further aid in portability, the system  600  can also include a handle hinge mounted to the left side of the housing  602 , along with two rigidly mounted handles  612   a  and  612   b  mounted on the left and right sides of the housing  602 . The housing  602  can further include a removable top lid (not shown) and a front panel  615  hinged to a lower panel by hinges  616   a  and  616   b . The cover can include handles for aiding with removal. 
     The system  600  can include an AC power cable  618 , along with a frame for securing the power cable, both which can be located on the lower section of the left side of the housing  602 . A power switch  622 , which can also be located on the lower section of the left side, can enable an operator to restart the system software and electronics. 
       FIG. 3G  shows a front perspective view of the multiple use module  650  with the single use module  634  removed. As shown, the multiple use module  650  can include the cart  604  and the housing  602 , along with all of the components mounted to/in it. The multiple use module  650  also includes a bracket assembly  638  for receiving and locking into place the single use module  634 . An exemplary bracket assembly  638  is shown in  FIG. 3H . 
     In some embodiments, the housing  602  can include a fluid tight basin, which is configured to capture any perfusion fluid and/or any other fluid that may inadvertently leak from the upper portion of the housing  602  and prevent it from reaching the lower section of the housing  602 . Thus, in some embodiments, the basin can shield the electronic components of the system  600  from leaked fluid. In some embodiments, the basin  652  can be sized to accommodate the entire volume of fluids used in the system  600  at any particular time. 
     The system  600  can also include the operator interface module  146 , along with a cradle  623  for holding the operator interface module  146 . The operator interface module  146  can include a display  624  for displaying information to an operator. The operator interface module  146  can also include a rotatable and depressible knob  626  for selecting between multiple parameters and display screens. The knob  626  can also be used to set parameters for automatic control of the system  600 , as well as to provide manual control over the operation of the system  600 . In some embodiments, the operator interface module  146  can include its own battery and may be removed from the cradle  623  and used in a wireless mode. While in the cradle  623 , power connections can enable the operator interface module  146  to be charged. The operator interface module can also include control buttons for controlling the pump, silencing or disabling alarms, entering or exiting standby mode, and starting the perfusion clock, which initiates the display of data obtained during organ care. 
     Referring also to  FIG. 5 , the system  600  can also include a plurality of interconnected circuit boards for facilitating power distribution and data transmission to, from and within the system  600 . For example, the multiple use module  650  can include a front-end interface circuit board  636 , which optically and electromechanically couples to the front-end circuit board  637  of the single use module  650 . The system  600  can further include a main board  718 , a power circuit board  720 , and a battery interface board  711  located on the multiple use module  650 . The main board  718  can be configured to allow the system  600  to be fault tolerant, in that if a fault arises in the operation of a given circuit board, the main board  718  can save one or more operational parameters (e.g., pumping parameters) in non-volatile memory. When the system  600  reboots, it can then re-capture and continue to perform according to such parameters. Additionally, the system  600  can divide critical functions among multiple processors so that if one processor fails the remaining critical functions can continue to be served by the other processors. 
     2. Power System 
     Referring also to  FIG. 4 , the multiple-use portion of the system  600  can include a power subsystem  148  that is configured to provide power to the system  600 . The power subsystem  148  can provide power to the system  600  using swappable batteries and/or an external power source. In some embodiments, the power subsystem  148  can be configured to switch between external power and an onboard battery, without interruption of system operation. The power subsystem  148  can also be configured to automatically allocate externally supplied power between powering the system  600 , charging the batteries, and charging internal batteries of the operator interface module  146 . The batteries in the power system can be used as the primary power source and/or as a backup power source in the event the external power source fails or becomes insufficient. Additionally, the power system  148  can be configured to be compatible with multiple types of external power sources. For example, the power system can be configured to receive multiple input voltages (e.g., 100V-230V), multiple frequencies (e.g., 50-60 Hz), single phase power, three-phase power, AC, and/or DC power. Additionally, in some embodiments the operator interface module  146  can have its own battery  368 . 
     The housing  602  can include a battery bay  628  that is configured to hold one or more batteries  352 . In embodiments with more than one battery, the battery bay  628  can also include a lockout mechanism  632  that is configured to prevent more than one battery from being removed from the battery bay  628  at any given time while the system  600  is operating. This feature can provide an additional level of fault tolerance to help ensure that a source of power is always available. The system  600  can also include a tank bay  630  that can be configured to receive one or more tanks of gas. 
     Referring to the conceptual drawing of  FIG. 5  cabling  731  can bring power (such as AC power  351 ) from a power source  350  to the power circuit board  720  by way of connectors  744  and  730 . The power supply  350  can convert the AC power to DC power and distribute the DC power as described above. The power circuit board  720  can couple DC power and a data signal  358  via respective cables  727  and  729  from the connectors  726  and  728  to corresponding connectors  713  and  715  on the front-end interface circuit board  636 . Cable  729  can carry both power and a data signal to the front-end interface board  636 . Cable  727  can carry power to the heater  110  via the front-end interface board  636 . The connectors  713  and  715  can interfit with corresponding connectors  712  and  714  on the front-end circuit board  637  on the single use module  634  to provide power to the single use module  634 . 
     7 The power circuit board  720  can also provide DC power  358  and a data signal from the connectors  732  and  734 , respectively, on the power circuit board  720  to corresponding connectors  736  and  738  on the main circuit board  718  by way of the cables  733  and  735 . The cable  737  can couple DC power  358  and a data signal from a connector  740  on the main circuit board  718  to the operator interface module  146  by way of a connector  742  on the operator interface module cradle  623 . The power circuit board  720  can also provide DC power  358  and a data signal from connectors  745  and  747  via cables  741  and  743  to connectors  749  and  751  on a battery interface board  711 . Cable  741  can carry the DC power signal and cable  743  can carry the data signal. Battery interface board  711  can distribute DC power and data to the one or more batteries  352  (in  FIG. 5 , batteries  352   a ,  352   b , and  352   c ), which can contain electronic circuits that allow them to communicate the respective charges so that the controller  150  can monitor and control the charging and discharging of the one a more batteries  352 . 
     3. Perfusion Fluid Pump 
     The system  600  can include a pump  106  that is configured to pump perfusate through the organ care system. The perfusate is typically a blood product-based perfusion fluid that can mimic normal physiologic conditions. In some embodiments, the perfusate can be a synthetic blood substitute solution and/or the perfusate can be a blood product in combination with a blood substitute product. In the embodiments where the perfusion fluid is blood-product based, it typically contains red blood cells (e.g., oxygen carrying cells). The perfusate is described more fully below. 
     In some embodiments, the pump  106  can have a systolic phase and a diastolic phase. The amount of perfusate pumped by the pump  106  can be varied by changing one or more characteristics of the pump itself. For example, the number of strokes per minute and/or the stroke displacement can be changed to achieve the desired flow rate and pressure characteristics. In some embodiments, the pump  106  can be configured to use a stroke rate of 1-150 st/min and a displacement of 0.1-1.5″. More specifically, however, a nominal stroke rate of 60 st/min±5 st/min can be used with a displacement of 0.5″. These values are exemplary only and values outside of these ranges can also be used. By varying the characteristics of the pump  106  flow rates of between 0.0 and 10 L/min can be achieved. 
     In some embodiments, a perfusion fluid pump  106  is split into two separable portions: a pump driver portion located in the multiple-use portion  650  and a pump interface assembly in the single-use portion  634 . This interface assembly of the single-use portion can isolate the pump driver of the multiple-use portion from direct blood biologic contact. 
       FIGS. 6A-6D  show an exemplary embodiment of the pump  106 .  FIGS. 6A-6C  show various views of a pump interface assembly  300  according to an exemplary embodiment.  FIG. 6D  shows a perspective view of an exemplary pump-driver portion  107  of the perfusion fluid pump  106 .  FIG. 6E  shows the pump interface assembly  300  mated with the pump-driver portion  107  of the perfusion fluid pump assembly  300 , according to one exemplary embodiment. 
     The pump interface assembly  300  includes a housing  302  having an outer side  304  and an inner side  306 . The interface assembly  300  includes an inlet  308  and an outlet  310 . The pump interface assembly  300  can also include inner  312  and outer  314  O-ring seals, two deformable membranes  316  and  318 , a doughnut-shaped bracket  320 , and half-rings  319   a  and  319   b  that fit between the o-ring  314  and the bracket  320 . The half-rings  319   a  and  319   b  can be made of foam, plastic, or other suitable material. 
     The inner O-ring  312  can fit into an annular track along a periphery of the inner side  306 . The first deformable membrane  316  can mount over the inner O-ring  312  in fluid tight interconnection with the inner side  306  of the housing  302  to form a chamber between an interior side of the first deformable membrane  316  and the inner side  306  of the housing  302 . A second deformable membrane  318  can fit on top of the first deformable membrane  316  to provide fault tolerance in the event that the first deformable membrane  316  rips or tears. Illustratively, the deformable membranes  316  and  318  can be formed from a thin polyurethane film (about 0.002 inches thick). However, any suitable material of any suitable thickness may be employed. Referring to  FIGS. 6A and 6B , the bracket  320  can mount over the second deformable membrane  318  and the rings  319   a  and  319   b  and can affix to the housing  302  along a periphery of the inner side  306 . Threaded fasteners  322   a - 322   i  can attach the bracket  320  to the housing  302  by way of respective threaded apertures  324   a - 324   i  in the bracket  320 . The outer O-ring  314  can interfit into an annular groove in the bracket  320  for providing fluid tight seal with the pump assembly  106 . Prior to inserting O-ring  314  into the annular groove in bracket  320 , the half-rings  319   a  and  319   b  are typically placed in the groove. The O-ring  314  can then be compressed and positioned within the annular groove in bracket  320 . After being positioned within the annular groove, the O-ring  314  can expand within the groove to secure itself and the half-rings  319   a  and  319   b  in place. 
     The pump interface assembly  300  can also include heat stake points  321   a - 321   c , which project from its outer side  304 . The points  321   a - 321   c  can receive hot glue to heat-stake the pump interface assembly  300  to a C-shaped bracket  656  of the single use portion of the system  300 . 
     As shown in  FIG. 6C , the fluid outlet  310  includes an outlet housing  310   a , an outlet fitting  310   b , a flow regulator ball  310   c  and an outlet port  310   d . The ball  310   c  is sized to fit within the outlet port  310   d  but not to pass through an inner aperture  326  of the outlet  310 . The fitting  310   b  is bonded to the outlet port  310   d  (e.g., via epoxy or another adhesive) to capture the ball  310   c  between the inner aperture  326  and the fitting  310   b . The outlet housing  310   a  is similarly bonded onto the fitting  310   b.    
     In operation, the pump interface assembly  300  is configured and aligned to receive a pumping force from a pump driver  334  of the perfusion fluid pump assembly  106  and translate the pumping force to the perfusion fluid  108 , thereby circulating the perfusion fluid  108  to the organ chamber assembly  104 . According to the exemplary embodiment, the perfusion fluid pump assembly  106  can include a pulsatile pump having a driver  334 , which can contact the membrane  318 . The fluid inlet  308  can draw perfusion fluid  108 , for example, from the reservoir  160 , and provide the fluid into the chamber formed between the inner membrane  316  and the inner side  306  of the housing  302  in response to the pump driver moving in a direction away from the deformable membranes  316  and  318 , thus deforming the membranes  316  and  318  in the same direction. 
     As the pump driver moves away from the deformable membranes  316  and  318 , the pressure head of the fluid  108  inside the reservoir  160  causes the perfusion fluid  108  to flow from the reservoir  160  into the pump assembly  106 . In this respect, the pump assembly  106 , the inlet valve  191  and the reservoir  160  are oriented to provide a gravity feed of perfusion fluid  108  into the pump assembly  106 . At the same time, the flow regulator ball  310   c  is drawn into the aperture  326  to prevent perfusion fluid  108  from also being drawn into the chamber through the outlet  310 . It should be noted that the outlet valve  310  and the inlet valve  191  are one-way valves in the illustrated embodiment, but in alternative embodiments the valves  310  and/or  191  are two-way valves. In response to the pump driver  334  moving in a direction toward the deformable membranes  316  and  318 , the flow regulator ball  310   c  moves toward the fitting  310   b  to open the inner aperture  326 , which enables the outlet  310  to expel perfusion fluid  108  out of the chamber formed between the inner side  306  of the housing  302  and the inner side of the deformable membrane  316 . A separate one-way inlet valve  191 , shown between the reservoir  160  and the inlet  308  in  FIG. 1 , stops any perfusion fluid from being expelled out of the inlet  308  and flowing back into the reservoir  160 . 
     In embodiments of the system  600  that are split into the single use module  634  and the multiple use module  650 , the pump assembly  107  can rigidly mount to the multiple use module  650 , and the pump interface assembly  300  can rigidly mount to the disposable single use module  634 . The pump assembly  106  and the pump interface assembly  300  can have corresponding interlocking connections, which mate together to form a fluid tight seal between the two assemblies  107  and  300 . 
     More particularly, as shown in the perspective view of  FIG. 6D , the perfusion fluid pump assembly  107  can include a pump driver housing  338  having a top surface  340 , and a pump driver  334  housed within a cylinder  336  of the housing  338 . The pump driver housing  338  can also include a docking port  342 , which includes a slot  332  sized and shaped for mating with a flange  328  projecting from the pump interface assembly  300 . The top surface  340  of the pump driver housing  338  can mount to a bracket  346  on the non-disposable multiple use module  650 . The bracket  346  can include features  344   a  and  344   b  for abutting the tapered projections  323   a  and  323   b , respectively, of the pump interface assembly  300 . The bracket  346  can also include a cutout  330  sized and shaped for aligning with the docking port  342  and the slot  332  on the pump driver housing  338 . 
     Operationally, the seal between the pump interface assembly  300  and the fluid pump assembly  107  can be formed in two steps, illustrated with reference to  FIGS. 6D and 6E . In a first step, the flange  328  is positioned within the docking port  342 , while the tapered projections  323   a  and  323   b  are positioned on the clockwise side next to corresponding features  344   a  and  344   b  on the bracket  346 . In a second step, as shown by the arrows  345 ,  347  and  349 , the pump interface assembly  300  and the fluid pump assembly  106  are rotated in opposite directions (e.g., rotating the pump interface assembly  300  in a counterclockwise direction while holding the pump assembly  106  fixed) to slide the flange  328  into the slot  332  of the docking port  342 . At the same time, the tapered projections  323   a  and  323   b  slide under the bracket features  344   a  and  344   b , respectively, engaging inner surfaces of the bracket features  344   a  and  344   b  with tapered outer surfaces of the tapered projections  323   a  and  323   b  to draw the inner side  306  of the pump interface assembly  300  toward the pump driver  334  and to interlock the flange  328  with the docking ports  342 , and the tapered projections  323   a  and  323   b  with the bracket features  344   a  and  344   b  to form the fluid tight seal between the two assemblies  300  and  106 . 
     In some embodiments, the system  100  can be configured such that the flow characteristics including pressure and flow volume of the perfusion fluid provided to the hepatic artery and the portal vein are directly controlled and under pressure generated by the pump  106  (e.g., the hepatic artery and portal veins can be in fluid pressure communication with the pump  106 ). This embodiment is different from an embodiment where a pump provides perfusion fluid to a reservoir (e.g., a reservoir located above the liver) and then uses gravity to provide fluid pressure to the liver. 
     4. Solution Infusion Pump 
     The system  600  can include a solution pump  631  that can be configured to inject one or more solutions into the perfusion module circuit. In some embodiments of the organ care system  600 , the solution pump  631  can be an off-the-shelf pump such as a MedSystem III from CareFusion Corporation of San Diego, Calif., and/or can be a solution pump as described below with respect to  FIGS. 7A-7P . The infusion solutions provided by the solution pump  631  can be used to, for example provide ongoing management of the organ such as inotropic support, glucose control, pH control. Additionally, while the solution pump  631  is generally considered part of the multiple use module  650 , parts of the solution pump  631  can be single use and replaced each time the system is used. 
     The solution pump  631  can be configured to provide one or more solutions simultaneously (also referred to has having one or more channels). In some embodiments, the solution pump  631  can provide three solutions: a maintenance solution, bile salts, and a vasodilator such as epoprostenol sodium. Each of these solutions are described more fully below. The solution pump  631  can support multiple infusion rates (e.g., from 1 to 200 ml/hr, although higher/lower rates are also possible). The infusion rate can be adjustable in time increments (e.g., 1 ml/hour increment, although higher/lower rates are possible) and changes to the infusion rate typically take effect within five seconds, although this is not required. At infusion rates of 10 ml/hr and below, the infused volume can be accurate to within +/−10% of the infusion rate set point, although this is not required. At infusion rates above 10 ml/hr, the infused volume can be accurate to within +/−5% of the infusion rate set point, although this is not required. 
     The solution pump can be configured to maintain any required accuracy with input pressures (static pressures relative to the solution pump line connection) of 0 to −50 mmHg on the solution side and 0 to +220 mmHg on the organ side. Preferably, infusions should not have any flow discontinuities greater than three seconds. After the solution pump has been de-aired, air bubbles larger than 50 uL are typically not injected into the perfusion module. In some embodiments, the portion of the line between the solution pump  631  and the organ can include a valve (e.g., a pinch valve) to further control the flow of solution to the organ. The solution pump  631  can provide status information for each channel such as infusion state and error. 
     The solution pump  631  can be used with one or more disposable cartridges that provide the solution. For example, the portion of the line between the solution supply and the solution pump  631  can include a spike to connect to an IV bag. In embodiments that include a disposable cartridge to supply the solution, the cartridge should be capable of operating for at least 24 hours. 
     The solution pump  631  can be configured to be controlled via one or more communication ports. For example, the solution pump  631  can be controlled via commands received over via a serial port, a network (e.g., Ethernet, WiFi), and/or cellular communications. Various aspects of the solution pump  631  can be controlled such as initial available volume of solution for each channel, infusion state (e.g., infusing or paused). A general and/or alarm status for each channel can also be accessible via the communication port. The status for each channel can include an indication of: whether a disposable cartridge is present, an initial volume is available, an infusing state, an infusing rate, time remaining until empty, and total volume infused. Additionally, the solution pump  631  can be configured so that each channel has fault-mode infusion rate capable of being written/read via the communication port. In some embodiments sensors disposed throughout the organ care system  600  can be connected (directly or indirectly through the controller  150 ) to facilitate automatic control the solution pump  631  by the controller  150  using an open or closed feedback loop. 
     The solution pump  631  can be configured to indicate when failures occur. For example, when a failure or occlusion is detected the solution pump  631  can illuminate a fault indicator associated with the faulted channel and/or send a notification via the communication port. The solution pump  631  can be configured to pause the infusion in a channel that has faulted and can restart the infusion after the fault or occlusion has been cleared. In embodiments where the infusion rates are set via the communication port, in the event that signals to/from the communication port are lost, the solution pump  631  can be configured to set the infusion rate to a preprogrammed fault-mode infusion rate. 
     The solution pump  631  can include one or more fault detection algorithms/mechanisms. For example, if a hardware failure is detected the solution pump  631  can alert a device connected to the communication port that a hardware fault has occurred. If a solution and/or organ side occlusion is detected, the solution pump  631  can alert the device connected via communication port that the occlusion has occurred. The solution pump  631  can be configured to carry out self-tests including power on and background self-tests. The results of the self-tests can be indicated on the solution pump  631  itself and/or communicated via the communication port. 
     As noted above, the solution pump can be an off-the-shelf solution pump and/or a custom design pump. Referring to  FIGS. 7A-7P , an exemplary embodiment of a custom-designed solution pump  631  is shown and described. 
     Some embodiments of the solution pump disclosed herein can use a syringe connected to a motor to control the delivery of an infusion solution. By increasing the diameter of the syringe, the capacity of the syringe to hold fluid can be increased. This increased fluid capacity can reduce the number of times the syringe is exchanged for a new, pre-loaded syringe. However, syringes with an increased diameter can result in the loss of precision during the delivery of solution because as the diameter increases, the amount of solution delivered when the plunger is depressed one unit also increases. Another exemplary embodiment of the solution pump uses a relatively small diameter syringe that can allow for greater precision in the delivery of solution. However, the solution can quickly run out due to the syringe&#39;s low fluid capacity. Exchanging the syringe with a new, pre-loaded syringe can create problems such as introducing air bubbles, interrupting the solution delivery, causing an inconvenience for users, and creating accessibility challenges. Thus, in some embodiments, a relatively small diameter syringe can be connected to an external source of fluid solution and the perfusion circuit via fluid lines and a series of one-way valves. In these embodiments, as the syringe is depressed, solution can flow through a one-way valve and into the perfusion circuit. When the syringe is retracted, the solution can flow through another one-way valve from the external fluid source into the syringe to refill it with solution. Thus, some embodiments of this design can allow fine precision control of solution delivery (e.g., by using a smaller diameter syringe) while eliminating the need to replace a preloaded syringe with another. 
     Referring to  FIGS. 7A-7P , an exemplary embodiment of a solution pump  9000  is shown. In this embodiment, the solution pump  9000  can use a removable/replaceable cassette  9020  to provide infusion solutions.  FIGS. 7C and 7D  show an exploded view of the solution pump  9000  and an infusion cassette  9020 , respectively. In this embodiment, the solution pump  9000  includes three channels, and thus, is configured to provide up to three different solutions. Other embodiments can include more or fewer channels. 
     The solution pump  9000  can be a syringe pump driven by a stepper motors  9002   a ,  9002   b ,  9002   c . The stepper motors  9002  can rotate respective lead screws  9005 . Carriages  9042  with carriage covers  9004  communicate with the lead screw  9005  and can move back and forth along the screw  9005 . The inside of carriages  9042  can also be threaded with matching threads to facilitate movement along the lead screw  9005  as the lead screw  9005  rotates. Additionally, the carriages  9042  can also move along linear rails  9041  that facilitate movement back and forth along the lead screws  9005 . Pins  9003  can be attached to the carriage covers  9004  and to a carrier  9036  that is configured to hold a syringe plunger  9017  so that as the carriages  9042  move back and forth along the lead screws  9005 , the plunger can be depressed and retracted. The pins  9003  can be threaded to facilitate attachment to the carrier  9036 , although this is not required. In the embodiment shown in  FIGS. 7E, 7F, 7G, 7H , the carrier  9036  can be shaped to fit around and hold the plunger  9017 . The carrier  9036  can be manufactured in two pieces that can press fit together using protrusions  9045 , fit together via screws, and/or any other fastener to clamp the syringe plunger. 
     In some embodiments, the stepper motor  9002  can be configured to operate at different speeds depending on whether the syringe is being extended or compressed. For example, when the syringe is being compressed (e.g., during infusion) the motor can move at a low speed such as four steps per second, whereas when the syringe is being extended (e.g., during refill) the motor can be moved at high speed such as 16,000 steps per second. Other speeds are possible. Additionally, each stepper motor  9002  can include an optical encoder on a motor shaft enclosed therein (or elsewhere) that can be used to track the position and/or speed of the motor  9002 . Accordingly, the position of the plunger of the syringe can be calculated. 
     In the embodiment shown in  FIG. 7C , the stepper motors  9002   a ,  9002   b ,  9002   c  are positioned in parallel to one another, although other configurations are possible. The pins  9003  pass through slots  9008  in a top cover  9001  and can attach to the carrier  9036  that connects to a plunger  9017  of syringe  9016 . The connection between the carriage  9042  and the plunger  9017  via the pins  9003  and the carrier  9036  can be used to depress and retract the syringe, which can cause the syringe to provide fluid, or refill itself with fluid when properly connected. For example, as the stepper motor  9002  rotates the lead screw  9005  in a clockwise manner, the carriage  9042  and the carriage cover  9004  with pin  9003  connected to carrier  9036  and plunger  9017  can move in a direction to cause the plunger  9017  to depress and release fluid solution from the syringe  9016 . When stepper motor rotates in a counterclockwise manner, the carriage  9042  can move in an opposite direction and the plunger  9017  can be caused to retract, thereby refilling the syringe  9016  with fluid from a fluid source, such as an external IV bag. 
     The solution pump  9000  can include optical switch  9007  that can be used to detect when the syringe is in a “home” or other position. In some embodiments, the home position can be a position when the syringe is extended and filled with solution, although other home positions are possible. The optical switch  9007  can be U-shaped and can be configured to transmit an optical beam between the two upper portions of the U (e.g., by having a transmitter on one side and a receiver on the other). In some embodiments, when the carriage  9042  is in its home position, a flag  9006  on the carriage cover  9004  can interrupt the optical beam from the optical switch  9007 , thus providing information on the position of the syringe. The flag  9006  can be made of any material that interrupts the optical beam such as opaque plastic and/or metal. In some instances it can be possible that the solution pump  9000  loses track of the position of the carriage  9042  because of, for example, a malfunction. If this occurs, the carriage  9042  can return to the home position, leaving the syringe  9016  filled and the plunger  9017  extended. This can allow the pump  9000  reattain the position of the syringe without accidentally providing any additional solution. In some embodiments of the solution pump  9000 , an additional optical switch  9007  can be included to determine when the syringe is nearly or completely empty. 
     The solution pump  9000  can also include pressure sensors  9009  to detect blockages in the delivery line  9010  or output line  9011 . An alarm can indicate when the pressure sensors  9009  detect a blockage by sensing a pressure over or under predetermined thresholds. The pressure sensor can be any commercially available sensor suitable for this purpose. In one embodiment, the sensor can be a MEMSCAP SP854 transducer with hydraulic fluid and a diaphragm. The pressure sensors  9009  can extend through the openings  9012  in the top cover  9001 . 
     The stepper motor  9002 , linear rails  9041 , and pressure sensors  9009  can be mounted to the structural plate  9013 . A printed circuit board (“PCB”)  9015  can be mounted to the opposite side of the structural plate  9013  and include electronics used to operate the solution pump  9000 . The plate  9013  can be made out of aluminum or any other suitable material and can contain a flange  9014  to provide increased stiffness. The plate can also contain a series of mounting holes to provide a connection point to the top cover and bottom cover. 
     The top cover  9001  can engage a bottom cover  9018  to enclose the solution pump  9000 . The two parts can engage along the edges and can be secured with screws or another fastener. A mounting plate  9019  can attach to the bottom cover  9018  (labeled as  9015  in some drawings) and to, for example, the inner wall of the system  600 . The top cover  9001  can also include an opening  9025  for connector cables that can connect elsewhere in the system  600 , such as to the controller  150 . 
     The solution pump  9000  can engage an infusion cassette  9020  that contains the syringe  9016 . In one embodiment the top cover  9001  can include a boss  9023  with a pin. As shown in  FIGS. 7A, 7B , a tab  9021  on the infusion cassette  9020  can engage the pin on the boss  9023  to provide a connection between the solution pump  9000  and the infusion cassette  9020 . Additionally, the solution pump  9000  can engage the infusion cassette  9020  via a circumferential groove on the pressure sensors  9009  that can be received by a pinch release portion  9022  of the infusion cassette  9020 . 
     The infusion cassette  9020  can include the delivery line  9010  with an IV bag spike  9024  at one end that can be connected to an IV bag or other external source of solution. The other end of the delivery line  9010  can be connected to a one-way check valve  9026  that is designed to allow fluid to only flow away from the IV bag and toward the syringe  9016 . The one-way check valve  9026  can be connected to a connector  9027 . An output line  9011  can be connected to a second one-way check valve  9032  that is designed to allow fluid to only flow away from the syringe  9016  and towards a port  9034 . The one-way check valve  9032  can also be connected to the connector  9027 . The output line  9011  can include a filter  9033  that filters particulate and air from the solution. The filter  9033  can be any filter with hydrophobic properties that are suitable for this purpose. The output line  9011  can also be coupled to the port  9034  that connects to the perfusion module. Port  9034  can include a luer fitting. The output line  9011  can also include a roller clamp  9035  that can close the output line  9011 . During use, the roller clamp  9035  can be kept open to allow fluid to pass through the output line  9011 . 
     Referring to  FIGS. 7I-7K , the connector  9027  can be, for example, a Y-connector. The connector  9027  can include connectors  9043 ,  9044 . Connector  9043  can be connected to the delivery line  9010  and connector  9044  can be connected to the output line  9011 . Connector  9027  can also include vertical infusion line. The vertical infusion line can connect to a connector mount. The connector  9027  can also include an alignment tab  9028 . 
     Referring to  FIGS. 7L-7P , an exemplary connector mount  9029  is shown. Connector mount  9029  can include a connection port  9031  that can be coupled to the connector  9027  and a syringe mount  9030  that can be coupled to the syringe  9016 . A pressure membrane (not shown) can be placed in the connector mount  9029  to monitor the pressure in the fluid circuit between the syringe  9016 , the delivery line  9010 , and the output line  9011  (e.g., using the pressure sensor  9009 ). The pressure membrane can be attached to the connector mount  9029  at a location opposite the connection port  9031 . The connector mount  9029  can also be used to removably attach the cassette  9020  to the top cover  9001  using a snap connector. For example, wings  9055  can extend through openings in the top cover  9037 . By squeezing the wings  9055  together a bottom portion  9056  can be flexed outwards releasing it from a corresponding connector portion on, for example, the pressure sensor  9009 . 
     In one embodiment, the syringe  9016  can deliver fluid as the plunger  9017  is compressed by the movement of the carriage  9042  along the lead screw  9005  by the stepper motor  9002 . The fluid from the syringe can pass into the vertical infusion line, past the one-way check valve  9032 , into the output line  9011 , through the filter  9033 , and into the perfusion fluid being circulated in the system  600 . Once the plunger  9017  is nearly or fully compressed so that there is little or no fluid to deliver from the syringe, the syringe can be retracted, allowing fluid to pass from the IV bag (not shown), through delivery line  9010 , past the one-way check valve  9026 , into the vertical infusion line, and into the syringe  9016 , thus refilling the syringe. 
     The infusion cassette can include a top cover  9037  that can engage a bottom cover  9038 , thus enclosing the syringe  9016 . A gasket  9039  can provide a seal around slots  9008  in top cover  9001  to keep fluid from entering the solution pump  9000  through the slots  9008 . The gasket can be made of any suitable sealing material, including foam. A shipping lock  9040  can retain the plunger  9017  and carrier in the fully retracted position so that carriage  9042  can be engaged in the home position. One purpose of the shipping lock  9040  can be to ensure that the hole  9092  in carrier  9036  is at the correct location so that the drive pin  9003  protrudes into the hole  9092  when the user installs the cassette  9020 . The shipping lock  9040  can be removed before use. 
     As will be appreciated, the type and configuration of syringe used in the cassette  9020  can affect how the system is controlled. For example, as the bore of the syringe increases, less travel of the plunger is needed to provide a given amount of solution. Additionally, syringes can have different capacities which can affect how often the syringe needs to be refilled. Thus, it can be beneficial for the solution pump  9000  to know what kind of syringe is installed in cassette  9020 . Accordingly, in some embodiments the system  9000  includes a mechanism by which it can determine what type of syringe is included in the cassette  9020 . For example, in an embodiment of the solution pump  9000  is configured to work with two different types of syringes, the pump can include a magnet and Hall effect sensor that can be configured to determine which of the two types of syringes is being used. For example, the cassette  9020  can include a magnet having N and S poles. The magnet can be oriented so that only one of the two poles interacts with the Hall effect sensor. When the first type of syringe is used, the N pole can be configured to interact with the Hall effect sensor and, likewise, when the second type of syringe is used, the S pole can be configured to interact with the Hall effect sensor. By determining which of the two poles is interacting with the Hall effect sensor, the solution pump  9000  can determine which type of syringe is being used in the cassette  9020 . The sensor configuration is exemplary only, and other sensors can be used to determine which type of syringes being used in the cassette  9020 . 
     The solution pump  9000  can be controlled by one or more control systems. For example, the solution pump  9000  can be controlled by the controller  150  and/or can include an internal control system. Regardless of the location of the controller, the controller can be configured to know how many partial or full rotations of the stepper motor  9002  are required to provide the necessary amount of solution and/or to refill the syringe. Thus, for example, the controller can know that it takes 40 steps of the stepper motor to provide 1 mL of solution. In some embodiments, the amount of solution provided by the solution pump  9000  can be manually controlled and/or can be controlled automatically by the controller  150 . 
     The solution pump  631  can be configured to provide solution flow rates that vary between 0.5 and 200 mL/hr, although other rates are possible. 
     Some embodiments of the solution pump  631  can include a priming cycle that can be used to prime and eliminate air within the lines of the pump  631 . For example, a user can assemble a complete line set dry and perform priming cycle until air is eliminated. For example, each priming cycle can advance 3 mL of air (or solution) using a special fast-forward and fast refill movement. In some embodiments, the prime cycle is under user control and/or can be performed automatically. 
     In some embodiments, when the motor  9002  is operated at a high speed (e.g., during refill and/or priming), the high-speed cycle can include a ramp-up and ramp down periods going into and coming out of high-speed operation. These ramp-up and ramp down periods can be used to overcome the rotational inertia of the motor  9002 . This function can be implemented by the firmware and/or controller is controlling the pump  631  using, for example lookup tables that have been calculated to adjust the pulse rates of the motors  9002  for constant acceleration and/or deceleration. The ramp-up and ramp down periods can also be used during low-speed operation. 
     In some embodiments, the solution pump  631  can be configured to compensate for inherent backlash that can be caused when the direction of travel of the syringe is reversed. For example, fluid flow can be particularly affected by the backlash inherent in the motor  9002  and lead screw  9005 . Errors caused by backlash can affect the resumption of infusion flow after a refill cycle. To offset these possible errors, firmware within the pump and/or the controller can capture the pressure in the syringe chamber at the end of all infusion strokes. The fast refill cycle can then be executed and the firmware and/or controller can advance the plunger at a moderately fast rate until the pressure in the syringe chamber is equal to the pressure captured during the last infusion strokes. When that pressure is reached, all system backlash has typically been resolved and the pump can continue infusing at the desired rate. 
     While stepper motors typically provide the highest torque for a given motor size, and can be easy to drive, they can also consume high amounts of power and can generate large amounts of mechanical noise. Thus, in some embodiments of the pump  631 , firmware and/or the controller can include a dynamic torque function that can operate the motors  9002  at the minimal torque required at any given time. This can be accomplished using digital to analog converters that control the current limit of each stepper motor driver, which can in turn control the torque provided by the motor. Accordingly, stepper motor torque can be adjusted to efficiently provide the required motion. At rest, a small current can be provided to the motor to maintain its static position without slipping. At the start of each forward infusion stroke, the stepper motor can be run at the selected infusion rate with a predefined minimal torque. If the encoder indicates that the stepper is not moving as desired, the torque can be increased until the proper movement is achieved. In this way, the forward infusion stroke can be performed at the minimal torque required to do the job. 
     The solution pump  631  can also be configured to make up for slippage between the actual position and the desired position of the syringe plunger. For example, when firmware and/or the controller determines that the syringe position (e.g., provided by an encoder) has slipped behind the desired profile, it can double the rate until the syringe position catches up. This process of slipping, torque increase, and/or rate doubling can happen quickly enough to provide uninterrupted infusion at the selected rate. 
       FIG. 7Q  shows an exemplary embodiment of a microcontroller architecture that can be included in the solution pump  631 , although this is not required and other configurations are possible. In this embodiment, the microcontroller architecture includes a processor (e.g., PIC 18F8722 processor) that receives inputs from, for example, the controller  150 , pressure input sensors, motor current and diagnostic voltage sensors, Hall magnetic sensors, photo interrupters, and/or encoder inputs. Using the information it receives, the processor can provide feedback to the controller  150  and/or can control the stepper motor drive to actuate the syringes in the respective channels. 
     5. Gas System, Including Variable Delivery Rate Control 
     The multiple use module  650  can include an on-board gas supply such as one or more common gas cylinders that can fit into the gas tank bay  630  and/or an oxygen concentrator. The gas supply system can include: i) one or more regulators to reduce the pressure of the gas provided by one or more gas cylinders, ii) pressure sensors that are configured to measure the pressure in the gas supply, and ii) gas pressure gauge that can provide a visual indication of the fullness of the gas supply. Each of these components can be manually controlled and/or can be connected and automatically controlled by the controller  150 . For example, the controller  150  can automatically regulate the gas flow into the gas exchanger  114 . While the gas provided by the gas provided by the gas source can vary, in some embodiments, the gas supply can provide a gas comprised of 85% 02, 1% CO 2 , and the balance N 2  with a blend process accuracy of 0.030%, while in some embodiments the gas supply can be between 50% 02 and 95% O 2  and the balance N 2  and/or Ar. In some embodiments the multiple gasses can be supplied premixed from a single cylinder or can be provided from multiple gas cylinders and mixed within the system  600 . In some embodiments gas can be supplied from a portable oxygen concentrator, such as the Oxus Portable Oxygen Concentrator from Oxus, Inc. of Rochester Hills, Mich., or a Freestyle series portable oxygen concentrator available from AirSep, or Buffalo, N.Y. 
     In some embodiments the system  600  can support a gas flow rate of 0-1000 mL/min and can have a set point resolution of 50 ml/min with a gas flow delivery accuracy of ±20% in the range from 200-1000 mL/min. The system  600  and the gas supply  172  can be configured to provide a gas flow in the event of a circulatory pump fault. The ranges listed above are exemplary, and values outside of those specifically identified can also be used. Lastly, in some embodiments the system  600  and the gas supply  172  can be configured to provide an indicator of the pressure in the gas supply  172  via multiple interfaces (e.g., via a gauge on the gas supply  172  and/or the operator interface module  146 ). 
     6. Controller and User Interface 
     The system  600  can include a control system (e.g., controller  150 ) that controls the overall operation of the system  600  and the components used therein. At a general level, the control system can include an onboard computer system that is connected to one or more of the components in the system  600  and to one or more sensors, network connections, and/or user inputs. Using the information obtained from the sensors, network connections, and/or user inputs, the control system can control the various components in the system  600 . For example, the control system can be used to implement one or more open or closed feedback systems to control operation of the system  600 . The control system can be a common off-the-shelf computer and/or a specially designed computer system. It should be noted that although the system  600  is described conceptually with reference to a single controller, the control of the system  600  can be distributed in a plurality of controllers or processors. For example, any or all of the described subsystems may include a dedicated processor/controller. Optionally, the dedicated processors/controllers of the various subsystems may communicate with and via a central controller/processor. For example, in some embodiments, a single controller located in the multiple-use module  650  can control the entire system  600 , in other embodiments a single controller located in the single-use module  634  can control the entire system  600 , and in still other embodiments, the controller can be split between the single-use module  634  and the multiple-use module  650 . 
     As a further example, in some embodiments, the controller  150  can be located on the main circuit board  718  and can perform all control and processing required by the system  600 . However, in other embodiments, the controller  150  can distributed, locating some processing functionality on the front-end interface circuit board  636 , some on the power circuit board  720 , and/or some in the operator interface module  146 . Suitable cabling can be provided between the various circuit boards, depending on whether and the degree to which the controller  150  is distributed within the system  600 . 
       FIG. 8  depicts an exemplary block diagram of an illustrative control scheme for the system  600 . For example, the system  600  can include a controller  150  for controlling operation of the system  600 . As shown, the controller  150  can connect interoperationally several subsystems: an operator interface  146  that can assist an operator in monitoring and controlling the system  600  and in monitoring the condition of the organ; a data acquisition subsystem  147  that can include various sensors for obtaining data relating to the organ and to the system  600 , and for conveying the data to the controller  150 ; a power management subsystem  148  for providing fault tolerant power to the system  600 ; a heating subsystem  149  for providing controlled energy to the heater  110  for warming the perfusion fluid  108 ; a data management subsystem  151  for storing and maintaining data relating to operation of the system  600  and with respect to the liver; and a pumping subsystem  153  for controlling the pumping of the perfusion fluid  108  through the system  600 . 
     An exemplary embodiment of the data acquisition subsystem  147  will now be described with reference to  FIG. 9 . In this embodiment, the data acquisition subsystem  147  include sensors for obtaining information pertaining to how the system  600  and the liver is functioning. The data acquisition subsystem  147  can provide this information to the controller  150  for processing. For example, the data acquisition subsystem  147  can be coupled to the following sensors: temperature sensors  120 ,  122 ,  124 ; pressure sensors  126 ,  128 ,  130  (which can be the pressure sensors  130   a ,  130   b  referred to elsewhere herein); flow rate sensors  134 ,  136 ,  138 ; the oxygenation/hematocrit/temperature sensor  140 ; Hall sensors  388 ; shaft encoder  390 ; battery sensors  362   a ,  362   b ,  362   c ; external power available sensor  354 ; and operator interface module battery sensor  370 ; a gas pressure sensor  132 . How the system  600  uses the information from the data acquisition subsystem  147  will now be described with regard to the heating  149 , power management  148 , pumping  153 , data management  151 , and operator interface  146  subsystems. 
     Referring to  FIG. 10 , this figure depicts an exemplary block diagram of the power management system  148  for providing fault tolerant power to the system  600 . The system  600  can be powered by one of multiple sources such as an external power source (e.g., 60 Hz, 120 VAC in North America or 50 Hz, 230 VAC in Europe) or by any of the one or more batteries  352 . While the remainder of this description refers to an AC power source as the external power source, it is to be understood that a DC power source can also be used. The controller  150  can receive data from an AC line voltage availability sensor  354 , which can indicate whether the AC voltage  351  is available and/or sufficient for use by the system  600 . 
     In response to the controller  150  detecting that external power is not available, the controller  150  can signal the power switching circuitry  356  to provide system power from the one or more batteries  352 . The controller  150  can determine from the battery charge sensors  362  which of the one or more batteries  352  is most fully charged, and can then switch that battery into operation by way of the switching network  356 . The system can be designed to prevent interruptions in the operation of the system  600  as the power is switched from one source to another. 
     Alternatively, in response to the controller  150  detecting that suitable external power is available, the controller  150  can determine whether to use the external power for providing system power and for providing power to the user interface module  146 , for charging the one or more batteries  352 , and/or for charging the internal battery of user interface module  146 , which can also have its own internal charger and charging controller. To use available external power (e.g., AC power  141 ) the controller  150  can draw the external power into the power management system  148  by signaling through the switching system  164 . In the event that the external power source is AC, the power management system  148  can also receive the external AC and convert it to a DC for providing power to the system  600 . The power management system  148  can be universal and can handle any line frequencies or line voltages commonly used throughout the world. According to the illustrative embodiment, in response to a low battery indication from one or more of the battery sensors  362 , the controller  150  can also direct power via the switching network  364  and the charging circuit  366  to the appropriate battery. In response to the controller  150  receiving a low battery signal from the sensor  370  (which can monitor a battery in the user interface module  146 ), it can also or alternatively direct a charging voltage  367  to the user interface battery  368 . In some embodiments, the power management subsystem  148  can select batteries to power the system  600  using an algorithm to best provide for battery longevity, including selecting in order of least-charged first as well as other factors, such as least number of charge cycles. If the battery that is currently being used to power the system  600  is removed by the user, the power management subsystem  148  can automatically switch to the next battery per the algorithm to continue powering the system  600 . 
     Referring to  FIG. 11 , an exemplary embodiment of the heating subsystem  149  is shown. The heating subsystem  149  can control the temperature of the perfusion fluid  108  within the system  600  through, for example, a dual feedback loop approach. In the first loop  251  (the perfusion fluid temperature loop), the perfusion fluid temperature thermistor sensor  124  provides two (fault tolerant) signals  125  and  127  to the controller  150 . The signals  125  and  127  are typically indicative of the temperature of the perfusion fluid  108  as it exits the heater assembly  110 . The controller  150  can regulate the drive signals  285  and  287  to the drivers  247  and  249 , respectively. The drivers  247  and  249  can convert corresponding digital level signals  285  and  287  from the controller  150  to heater drive signals  281  and  283 , respectively, having sufficient current levels to drive the first  246  and second  248  heaters to heat the perfusion fluid  108  to within a desired temperature range. In response to the controller  150  detecting that the perfusion fluid temperatures  125  and  127  are below the desired temperature range, it can set the drive signals  281  and  283  to the first  246  and second  248  heaters, respectively, to a sufficient level to continue to heat the perfusion fluid  108 . Conversely, in response to the controller  150  detecting that the perfusion fluid temperatures  125  and  127  are above the desired temperature range, it can decrease the drive signals  281  and  283  to the first  246  and second  248  heaters, respectively. In response to detecting that the temperature of the perfusion fluid  108  is within the desired temperature range, the controller  150  can maintain the drive signals  281  and  283  at constant or substantially constant levels. The temperature control system can be controlled to warm the perfusate to a temperature range between 0-50° C., and more specifically between 32-42° C., and even more specifically between 32-37° C. These ranges are exemplary only and the temperature control system can be controlled to warm the perfusate to any temperature range falling within 0-50° C. The desired temperature can be user-selectable and/or automatically controlled by the controller  150 . As used herein and in the claims, “normothermic” is defined a temperature between 34-37° C. 
     In some embodiments, the controller  150  can vary the drive signals  281  and  283 , which can control the first and second heaters, in substantially the same manner. However, this is not required. For example, each heater  246  and  248  may respond differently to a particular current or voltage level drive signal. In such a case, the controller  150  can drive each heater  246  and  248  at a slightly different level to obtain the same temperature from each. In some embodiments, the heaters  246  and  248  can each have an associated calibration factor, which the controller  150  stores and employs when determining the level of a particular drive signal to provide to a particular heater to achieve a particular temperature result. In certain configurations, the controller  150  can set one of the thermistors in dual sensor  124  as the default thermistor, and will use the temperature reading from the default thermistor in instances where the thermistors give two different temperature readings. In some embodiments, where the temperature readings are within a pre-defined range, the controller  150  can use the higher of the two readings. The drivers  247  and  249  can apply the heater drive signals  281  and  283  to corresponding drive leads  282   a  and  282   b  on the heater assembly  110 . 
     In the second loop  253  (the heater temperature loop), the heater temperature sensors  120  and  122  can provide signals  121  and  123 , indicative of the temperatures of the heaters  246  and  248 , respectively, to the controller  150 . According to the illustrated embodiment, a temperature ceiling can be established for the heaters  246  and  248  (e.g., by default, operator selection, or automatically determined by the controller  150 ), above which the temperatures of the heaters  246  and  248  are not allowed to rise. As the temperatures of the heaters  246  and  248  rise and approach the temperature ceiling, the sensors  121  and  123  can indicate the same to the controller  150 , which can then lower the drive signals  281  and  283  to the heaters  246  and  248  to reduce or stop the supply of power to the heaters  246  and  248 . Thus, while a low temperature signal  125  or  127  from the perfusion fluid temperature sensor  124  can cause the controller  150  to increase power to the heaters  246  and  248 , the heater temperature sensors  120  and  122  ensure that the heaters  246  and  248  are not driven to a degree that would cause their respective heater plates  250  and  252  to become hot enough to damage the perfusion fluid  108 . 
     In some embodiments, the controller  150  can be configured to maintain the perfusion fluid temperature between 0-50° C. In some embodiments the perfusate is maintained within a temperature range of 32−42° C., or in some more specific embodiments in the rage of 35-37° C. In some embodiments, the controller can be configured to limit the temperature of the heater plates  250  and  252  to 38° C., 39° C., 40° C., 41° C., or 42° C. All of the ranges and numbers identified herein are exemplary and values outside of these ranges can also be used. Lastly, to the extent that the claims recite “substantially” in connection with a specific temperature value or range, this means that the temperature is to be within the operational temperature swing range of the heater/control system used. For example, if the claimed temperature is “substantially 32° C.,” and a heater/control system is used in an accused product that maintains the temperature within ±5% of a desired value, then any temperature that is ±5% of 32° C. is “substantially 32° C.” 
     As can be seen, the second loop  253  can be configured to override the first loop  251 , if necessary, such that temperature readings from temperature sensors  120  and  122  indicating that the heaters  246  and  248  are approaching the maximum allowable temperature override the effect of any low temperature signal from the perfusion fluid temperature sensor  124 . In this respect, the subsystem  149  can ensure that the temperature of the heater plates  250  and  252  do not rise above the maximum allowable temperature, even if the temperature of the-perfusion fluid  108  has not reached the desired temperature value. This override feature can be particularly important during failure situations. For example, if the perfusion fluid temperature sensors  124  both fail, the second loop  253  can stop the heater assembly  110  from overheating and damaging the perfusion fluid  108  by switching control exclusively to the heater temperature sensors  120  and  122  and dropping the temperature set point to a fixed value. In some embodiments, the controller  150  can take into account two time constants assigned to the delays associated with the temperature measurements from the heaters  246  and  248  and perfusion fluid  108  to optimize the dynamic response of the temperature controls. 
     In some embodiments, the user can be provided with the option to disable the blood warming feature of the system  600 . In this manner, the system can more efficiently support cooling of the liver during the post-preservation chilling procedure. In some embodiments, the heater assembly  110  (or a separate device, such as a gas exchanger with integrated cooling interface) can function as a chiller to cool the temperature of the perfusion fluid. 
     Turning now to the operator interface subsystem  146 ,  FIGS. 12A-12G  show various exemplary display screens of the operator interface subsystem  146 . The display screens can enable the operator to receive information from and provide commands to the system  600 .  FIG. 12A  depicts an exemplary top level “home page” screen  400 . From the screen  400  an operator can typically access most if not all of the data available from the data acquisition subsystem  147  and can typically provide any desired commands to the controller  150 . For example, a user can monitor and adjust the pumping subsystem  153  via the screen  400 . As described in more detail in reference to  FIGS. 12B-12G , the screen  400  can also allow the operator to access more detailed display screens for obtaining information, providing commands and setting operator selectable parameters. 
     In this exemplary embodiment, the screen  400  includes various portions each displaying different pieces of information and/or accepting different inputs. However, screen  400  is exemplary only and the information displayed by the screen  400  can be customized by the user (e.g., using dialog  590  described below in  FIG. 12F ). The values displayed on the screen  400  can be updated at regular intervals such as once every second. In this particular example, the screen  400  includes the following portions:
         Portion  402  that displays the hepatic artery flow rate. This value can be an indication of the flow at the flow sensor  138   b.      Portion  404  that displays the portal vein flow rate. This value can be an indication of the flow at the flow sensor  138   a.      Portion  406  that displays the oxygen saturation (SvO 2 ) of the perfusion fluid leaving the liver as measured by, for example, the sensor  140 .   Portion  408  that displays the hematocrit (HCT) level of the perfusion fluid leaving the liver as measured by, for example, the sensor  140 .   Portion  410  that displays the desired and measured temperature of the perfusate. In this embodiment, the larger, top number represents the measured temperature whereas the smaller number listed below represents the temperature at which the desired perfusate temperature is set. The temperature can be measured from one of more locations such as at the output of the heater assembly  110  using the temperature sensors  120  and  122 , and in some embodiments sensor  140 .   Portion  412  that displays the flow rate as measured by flow sensor  136 .   Portion  414  that displays systolic/diastolic pressure in the hepatic artery. The number in parentheses below the systolic/diastolic pressures is an arithmetic mean of the pressure waveform. This systolic/diastolic/mean pressure in the hepatic artery can be determined by the pressure sensor  130   a.      Portion  416  that displays a waveform of the hepatic artery pressure over time.   Portion  418  that displays systolic/diastolic pressure in the portal vein. Number in parentheses below the systolic/diastolic pressures is an arithmetic mean of the two. The systolic/diastolic pressure in the portal vein can be determined by the pressure sensor  130   b.      Portion  420  that displays a waveform of the portal vein pressure over time.   Portion  422  that displays the hepatic artery pressure averaged over time (e.g., two minutes).   Portion  424  that displays the hepatic artery flow rate averaged over time (e.g., two minutes).   Portion  426  that a graphical representation of the values from portion  422  and  424  over time. In this embodiment, the graph represents a 3½ hour time window. In some embodiments, the portion  426  can be controlled by the user to show different periods of time.   Portion  428  that displays an icon showing that the perfusion pump is running.   Portion  429  (which is not illuminated in this example) can show an organ type indicator that indicates which organ is being perfused and which mode of operation is being used. For example, an “M” can be used to indicate that the system  600  is in a maintenance mode.   Portion  430  that displays the status of a storage medium included in the system  600  (e.g., an SD card).   Portion  432  that displays the flow rate from the onboard gas supply. This portion can also display the amount of time remaining before the onboard gas supply runs out.   Portion  434  that displays the status of the power supply system. In this embodiment, the system  600  includes three batteries, where each battery has a corresponding status indicator showing the degree to which the battery is charged. This portion also indicates whether the system  600  is connected to an external power source (by showing a plug icon). In some embodiments, this portion can also include a numerical indication of the amount of time that the batteries can run the system  600  in the current mode of operation.   Portion  436  that displays the status and charge remaining of the battery included in the operator interface module  146 . This portion can also include an indication of the amount of time remaining for which the battery in the operator interface module  146  can support it in a wireless mode of operation.   Portion  438  that displays the status of a network and/or cellular connection. This portion can also identify whether the operator interface module  146  is operating in a wireless  464  fashion, along with a graphical representation  463  of the strength of the wireless connection between the operator interface module  146  and the remainder of the system  600 .       

     Additional portions can be displayed to show when one or more alarms and/or portions of the system  600  have been disabled by the user. 
     As can be seen in  FIG. 12A-12G  some portions can also include alarm range indicators (e.g., indicator  440 ) that indicates where the current value falls within an allowable range. Each portion can also include an alarm indicator (not shown) indicating that the respective values are outside of the range indicated by the corresponding range indicator. The range indicator for each respective value can be tied to the alarm values set in dialog  512  or independently set by the user. The screen  400  can be implemented on a touch screen interface. In portions that accept user input, the user can touch a specific portion to change the value therein using the knob  626 . 
     Referring to  FIGS. 12B, 12C, and 12D , a user can select to enter a configuration menu  484 . In some embodiments of the system, the configuration menu  484  can be limited to a portion of the screen so that the user can continue to monitor the information displayed on the screen. Using the configuration menu, the user can program desired operational parameters for the system  600 . In this embodiment of the configuration menu  484 , the menu has three tabbed pages  484   a ,  484   b ,  484   c  (“Liver,” “System,” and “Actions”). 
     In tabbed page  484   a , the Liver tab is shown. In this tab the user is able to enter alarm dialog  512  (described below with respect to  FIG. 12E ), select the data shown in the middle graphic frame, select the data shown in the bottom graphic frame, set the desired gas flow rate, and set the desired temperature. Changes made in the tabbed page  484   a  can be reflected in the screen  400 . 
     In tabbed page  484   b , the System tab is shown. In this tab, the user can adjust one or more display features of the system  600 . For example, the user can select which units are used to display the various measurements (e.g., pascal versus mmHg), can restore factory defaults, can store new default settings, and can restore saved default settings. From this tab a service technician can also enable a wireless connection from a service laptop to the system  600 . Changes made in the tabbed page  484   b  can be reflected in the screen  400 . 
     In tabbed page  484   c , the Actions tab is shown. In this menu, the user can display the status of the machine, display a summary of all of the alarms, can adjust the scale of displayed measurements, and/or can interact with the data stored by the system  600 . For example, in some embodiments the user can withdraw a sample of the perfusion fluid and perform an external test on it. The user can then manually enter the value obtained by the external test into the data stream being maintained by the system  600 . In this manner, system  600  can include all data relevant to the organ being transplanted, regardless of whether that data was generated externally from the system  600 . 
     Referring to  FIG. 12E , alarm dialog  512  displays the parameters associated with the operation of the system  600 . In this embodiment, there are alarms for hepatic artery flow (HAF), portal vein pressure (PVP), hepatic artery pressure (HAP), inferior vena cava pressure (IVCP), perfusion fluid temperature (Temp), oxygen saturation (SvO 2 ), hematocrit (HCT). More of fewer parameters can be included in the dialog  512 . Row  514  indicates an upper alarm limit (e.g., a value above this number will cause an alarm) and row  516  indicates a lower alarm limit (e.g., a value below this number will cause an alarm). The user can also enable/disable individual alarms by selecting the associated alarm icon in row  518 . The icons in row  518  can indicate whether an individual alarm is enabled or disabled (e.g., in  FIG. 12E  the alarm for IVCP is disabled). The alarm limits can be predetermined, user settable, and/or determined in real-time by the controller  150 . In some embodiments, the system  600  can be configured to automatically switch between sets of alarm limits for a given flow mode upon changing the flow mode. Changes made in the dialog  512  can be reflected in the screen  400 . 
       FIG. 12F  shows an exemplary user interface (dialog  590 ) in which a user can select what the various portions of screen  400  display. For example, in  FIG. 12F , the user can choose to display the realtime waveform of the hepatic artery pressure, portal vein pressure or IVC pressure, or choose to display trend graphs for those or other measured parameters in a portion of the screen  400 . Other waveforms can also be calculated and displayed by the controller  150 . 
       FIG. 12G  shows an exemplary user interface (dialog  592 ) in which a user can adjust parameters of the pumping subsystem  153 . In this example, the user can adjust the pump flow and turn the pump on/off. 
     The data management subsystem  151  can receive and store data and system information from the various other subsystems. The data and other information can be downloaded to a portable memory device and organized within a database, as desired by an operator. The stored data and information can be accessed by an operator and displayed through the operator interface subsystem  146 . The data management system  151  can be configured to store in the information in one or more places. For example, the data management subsystem  151  can be configured to store data in storage that is internal to the system  600  (e.g., a hard drive, a flash drive, an SD card, a compact flash card, RAM, ROM, CD, DVD) and/or external to the system (e.g., a remote storage memory or Cloud storage). 
     In embodiments using external storage, the data management subsystem  151  (or another part of the controller  150 ) can communicate with the external storage over various communication connections such as point-to-point network connections, intranets, and the Internet. For example, the data management subsystem  151  can communicate with a remote storage medium or “the Cloud” (e.g., data servers and storage devices on a shared and/or private network) via a WiFi network (e.g., 802.11), a cellular connection (e.g., LTE), a Bluetooth (e.g., 802.15), infrared connection, a satellite-based connection, and/or a hard-wired network connection (e.g., Ethernet). In some embodiments, the data management subsystem can be configured to automatically detect the best network connection to communicate with the remote storage device and/or Cloud. For example, the data management subsystem can be configured to default to known WiFi networks and automatically switch to a cellular network when no known WiFi networks are available. Remote and Cloud based embodiments are discussed more fully below. 
     Referring to  FIG. 12H , the pumping subsystem  153  will now be described in further detail. The controller  150  can operate the pumping subsystem  153  by sending a drive signal  339  to a brushless three-phase pump motor  360  using Hall Sensor feedback. The drive signal  339  can cause the pump motor shaft  337  to rotate, thereby causing the pump screw  341  to extent and retract the pump driver  334 . According to the illustrative embodiment, the drive signal  339  is controlled to change a rotational direction and rotational velocity of the motor shaft  337  to cause the pump driver  334  to extract and retract cyclically. This cyclical motion can pump the perfusion fluid through the system  600 . 
     The controller  150  can receive a first signal  387  from the Hall sensors  388  positioned integrally within the pump motor shaft  337  to indicate the position of the pump motor shaft  337  for purposes of commutating the motor winding currents. The controller  150  can receive a second higher resolution signal  389  from a shaft encoder sensor  390  indicating a precise rotational position of the pump screw  341 . From the current motor commutation phase position  387  and the current rotational position  389 , the controller  150  can calculate the appropriate drive signal  339  (both magnitude and polarity) to cause the necessary rotational change in the motor shaft  337  to cause the appropriate position change in the pump screw  341  to achieve the desired pumping action. By varying the magnitude of the drive signal  339 , the controller  150  can vary the pumping rate (e.g., how often the pumping cycle repeats) and by varying the rotational direction changes, the controller  150  can vary the pumping stroke volume (e.g., by varying how far the pump driver  334  moves during a cycle). Generally speaking, the cyclical pumping rate regulates the pulsatile rate at which the perfusion fluid  108  is provided to the liver, while (for a given rate) the pumping stroke regulates the volume of perfusion fluid provided to the liver. 
     Both the rate and stroke volume affect the flow rate, and indirectly the pressure, of the perfusion fluid  108  to the liver. As described herein, the system  600  can include three flow rate sensors  134 ,  136  and  138 , and three pressure sensors  126 ,  128 , and  130 . The sensors  134 ,  136 , and  138  can provide corresponding flow rate signals  135 ,  137  and  139  to the controller  150 . Similarly, the sensors  126 ,  128  and  130  can provide corresponding pressure signals  129 ,  131  and  133  to the controller  150 . The controller  150  can use all of these signals in feedback to ensure that the commands that it is providing to the perfusion pump  106  have the desired effect on the system  600 . In some instances, the controller  150  can generate various alarms in response to a signal indicating that a particular flow rate or fluid pressure is outside an acceptable range. Additionally, employing multiple sensors enables the controller  150  to distinguish between a mechanical issue (e.g., a conduit blockage) with the system  600  and a biological issue with the liver. 
     While the above discloses the use of three pressure sensors, this is not required. In many of the embodiments described herein only two pressure sensors are used (e.g., pressure sensors  130   a ,  130   b ). In this instance, the input for the third pressure sensor can be ignored. However, in some embodiments of the system disclosed herein a third pressure sensor can be used to measure the pressure in the perfusion fluid flowing from the inferior vena cava (or elsewhere in the system  100 ). In this instance, the controller  150  can process the pressure signal from the sensor as described above. 
     The pumping system  153  can be configured to control the position of the pump driver  334  during each moment of the pumping cycle to allow for finely tuned pumping rate and volumetric profiles. This can enable the pumping system  153  to supply perfusion fluid  108  to the liver with any desired pulsatile pattern. According to one illustrative embodiment, the rotational position of the shaft  337  can be sensed by the shaft encoder  390  and adjusted by the controller  150  at least about 100 increments per revolution. In another illustrative embodiment, the rotational position of the shaft  337  is sensed by the shaft encoder  390  and adjusted by the controller  150  at least about 1000 increments per revolution. According to a further illustrative embodiment, the rotational position of the shaft  337  is sensed by the shaft encoder  390  and adjusted by the controller  150  at least about 2000 increments per revolution. The position of the pump screw  341  and thus the pump driver  334  can be calibrated initially to a reference position of the pump screw  341 . 
     As described above, the system  600  can be manually controlled using the controller  150 . However, some or all of the control of the system can be automated and performed by the controller  150 . For example, the controller  150  can be configured to automatically control the pump  106  flow of the perfusion fluid (e.g., pressure flow rate), the solution pump  631 , the pump  106 , the gas exchanger  114 , the heater  110 , and/or the flow clamp  190 . Control of the system  600  can be accomplished using minimal, or even no intervention by the user. For example, the controller  150  can be programmed with one or more predetermined routines and/or can use information from the various sensors in the system  600  to implement open and/or closed feedback loops. For example, if the controller determines that the oxygenation level of the perfusion fluid flowing out of the IVC is too low or the CO 2  level is too high, the controller  150  can adjust the supply of gas to the gas exchanger  114  accordingly. As another example, the controller  150  can control the infusion of one or more solutions based on the sensor  140  and/or any other sensor in the system  600 . As a still further example, if the controller senses that the liver is producing too much CO 2 , the controller can reduce the temperature of the liver to 35° C. (assuming it was previously being maintained as a higher temperature) to reduce the metabolic rate, and accordingly the rate of CO 2  production or O 2  consumption. As yet another example, the controller  150  can modulate gas flow to the gas exchanger  114  based on measurements from one or more sensors in the system  600 . 
     In some embodiments, the controller  150  can be configured to control aspects of the system  600  as a function of lactate value in the perfusion fluid. In one embodiment, multiple perfusion fluid lactate values can be obtained over time. For example, a user can withdraw a perfusion fluid sample and use an external blood gas analyzer to determine a lactate value and/or the system  600  can use an onboard lactate sensor (e.g., a lactate sensor located in the measurement drain  2804 ). The lactate value can be measured in the IVC or elsewhere and can be repeated at predetermined time intervals (e.g., every 30 minutes). The controller  150  can analyze the trend of the lactate values over time. If the lactate is trending down or staying relatively even, this can be an indication that the liver is being properly perfused. If the lactate is trending upwards, this can be in indication of improper perfusion, which can result in the controller  150  increasing pump flow, adjusting the rate of infused vasodilator, and/or modifying the gas flow to the gas exchanger  114 . 
     Automating the control process can provide many benefits including providing finer control over the parameters of the system, which can result in a healthier liver and/or reducing the burden on the user. 
     In some embodiments, the system  600  can include a global positioning device to track the geographic location of the system. 
     C. Exemplary Single Use Module 
     Turning now to the single use module, an exemplary embodiment is described herein as the single-use module  634 , although other embodiments are possible. As noted above, this portion of the system  600  typically contains at least all of the components of the system  600  that come into contact with biological material such as the perfusate along with various peripheral components, flow conduits, sensors, and support electronics used in connection with the same. After the system  600  is used to transport an organ, the single-use module can be removed from the system  600  and discarded. A new (and sterile) single-use module can be installed into the system  600  to transport a new organ. In some embodiments, the module  634  does not include a processor, instead relying on the controller  150 , which can be distributed between the front-end interface circuit board  636 , the power circuit board  720 , the operator interface module  146 , and the main circuit board  718 , for control. However, in some embodiments, the single-use module can include its own controller/processor (e.g., on the front-end circuit board  637 ). 
     Referring to  FIGS. 13A-13H , an exemplary single use module  634  is shown.  FIGS. 13M-R  show another exemplary single use module  634  with an alternatively shaped organ chamber  104 . Note, however, in some of the views certain components have been omitted to clarify the drawings (e.g., some of the tubing connectors, ports, and/or clamps have been omitted). 
     The single-use module  634  can include a chassis  635  having upper  750   a  and lower  750   b  sections. The upper section  750   a  can include a platform  752  for supporting various components. The lower section  750   b  can support the platform  752  and can include structures for pivotably connecting with the multiple use module  650 . 
     The lower chassis section  750   b  can include a C-shaped mount  656  for rigidly mounting the perfusion fluid pump interface assembly  300 , and the projection  662  for sliding into and snap fitting with the slot  660 . In some embodiments, the lower chassis section  750   b  can also provide structures for mounting parts of the perfusion circuit including the following components: gas exchanger  114 , heater assembly  110 , reservoir  160 , perfusate flow compliance chambers  184 ,  186 . In some embodiments, the lower chassis section  750   b  can also contain, via appropriate mounting hardware, various sensors such as the sensor  140 , the flow rate sensors  136 ,  138   a ,  138   b , and the pressure sensors  130   a ,  130   b . The lower chassis section  750   b  can also mount the front-end circuit board  637 . This embodiment is exemplary only, and components listed above as being part of the lower chassis section  750   b  can be located elsewhere such as in the upper section  750   a  (e.g., the pressure sensors  130   a ,  130   b ). 
     The upper chassis section  750   a  can include the platform  752 . The platform  752  can include handles  753   a  and  753   b  formed therein to assist in installing and removing the single use module  634  from the multiple use module  650 , although the handles can be located elsewhere in the single use module  634 . The platform  752  can include one or more orifices (e.g.,  717 ) to allow tubing and/or other components to pass therethrough. The platform  752  can also include one or more integrally formed brackets (e.g.,  716 ) to hold components in place atop the platform  752 , such as the fluid injection and/or sampling ports described more fully below. The upper chassis section  750   a  can also include a flow clamp  190  for regulating the flow of perfusion fluid to the portal vein, as described more fully below. The organ chamber assembly  104  can be configured to mount to the platform  752  via one or more supports  719 . Referring specifically to  FIG. 13I , the organ chamber assembly  104  can be mounted so that the left and right sides (relative to the main drain) are at approximately a 15° angle with respect to the platform  752 . Doing so can help perfusion fluid drain from the organ chamber assembly  104 , especially during transient conditions that can be encountered during transport (e.g., takeoff and landing in an airplane). 
     1. Organ chamber 
     The system  600  can include an organ chamber that is configured to hold an ex vivo organ. The design of the organ chamber can vary depending on the type of organ. For example, the design of the organ chamber can vary depending on whether, for example, it is being used to transport a liver, a heart, and/or lungs. While the following description focuses on an organ chamber  104  that is configured to transport a liver, this embodiment is exemplary only, and other configurations are possible. For example, other configurations of the organ chamber  104  can also be used to transport a liver. 
     (i) Shape/Drain Structure 
     Referring to  FIGS. 14A-14H , an exemplary embodiment of the organ chamber  104  is shown from multiple views. In this embodiment, the organ chamber  104  includes a base  2802 , a front piece  2816 , a removable lid  2820 , and a support surface  2810  (which is described in detail with respect to  FIGS. 15A-15D ). In some embodiments, the organ chamber  104  can also include a pad  4500  to support the liver. The bottom of the organ chamber  104  can be configured with a quasi-funnel shape where the sides of the funnel are angled at approximately 15° relative to the platform  752 , this is illustrated more clearly in  FIG. 13I . 
     The general level, the base member  2802  can include one or more drains (e.g.,  2804 ,  2806 ), one more orifice (e.g.,  2830 ) for tubing, connectors, and/or instruments to be inserted inside of the organ chamber  104  while the lid (e.g.,  2820 ) is closed, one or more hinge portions (e.g.,  2832 ), and one or more mounting brackets (e.g.,  2834 ). In some embodiments, as shown in  FIG. 14I , the mounting brackets  2834  are molded. In some embodiments, the base member  2802  is configured to fit and support the support surface  2810 , on which the liver typically rests. The organ chamber  104  and the support surface  2810  can be made from any suitable polymer plastic, for example, polycarbonate. 
     The base  2802  of chamber  2204  can be shaped and positioned within the system  600  to facilitate the drainage of the perfusion medium from the liver  101 . The organ chamber  104  can have two drains: measurement drain  2804 , and main drain  2806 , which can receive overflow from the measurement drain. The measurement drain  2804  can drain perfusate at a rate of about 0.5 L/min, considerably less than perfusion fluid  250  flow rate through liver  101  of between and 1-3 L/min. The measurement drain  2804  can lead to sensor  140 , which can measure SaO 2 , hematocrit values, and/or temperature, and then leads on to reservoir  160 . The main drain  2806  can lead directly to the defoamer/filter  161  without passing through the sensor  140 . In some embodiments, the sensor  140  cannot obtain accurate measurements unless perfusion fluid  108  is substantially free of air bubbles. In order to achieve a bubble-free column of perfusate, base  2802  is shaped to collect perfusion fluid  108  draining from liver  101  into a pool that collects above the measurement drain  2804 . The perfusate pool typically allows air bubbles to dissipate before the perfusate enters drain  2804 . The formation of a pool above drain  2804  can be promoted by optional wall  2808 , which can partially block the flow of perfusate from measurement drain  2804  to main drain  2806  until the perfusate pool is large enough to ensure the dissipation of bubbles from the flow. Main drain  2806  can be lower than measurement drain  2804 , so once perfusate overflows the depression surrounding drain  2804 , it flows around and/or over wall  2808 , to drain from main drain  2806 . 
     In an alternate embodiment of the dual drain system, other systems are used to collect perfusion fluid into a pool that feeds the measurement drain. In some embodiments, the flow from the liver is directed to a vessel, such as a small cup  2838 , which feeds the measurement drain. The cup  2838  fills with perfusion fluid, and excess blood overflows the cup and is directed to the main drain and thus to the reservoir pool. In this embodiment, the cup  2838  performs a function similar to that of wall  2808  in the embodiment described above by forming a small pool of perfusion fluid from which bubbles can dissipate before the perfusate flows into the measurement drain on its way to the oxygen sensor. In still other embodiments of the measurement drain, a gradual depression can be formed in the bottom of the base  2802  around the measurement drain  2804  that performs the same function as the cup described above. 
     The top of organ chamber  104  can be covered with a sealable lid that includes front piece  2816 , removable lid  2820 , inner lid with sterile drape (not shown), and sealing piece  2818 . The removable lid  2820  can be hingedly and removably coupled to the base member  2802  via hinge portions  2832 . The sealing piece  2818  can seal the front piece  2816  and/or base  2802  to lid  2820  to create a fluid and/or airtight seal. The sealing piece  2818  can be made out of, for example, rubber and/or foam. In some embodiments, the front piece  2816  and lid  2820  is rigid enough to protect the liver  101  from physical contact, indirect or direct. 
     An alternative embodiment of the organ chamber is shown from multiple views in  FIGS. 141-14S . In this embodiment, the base  2802  of the organ chamber  104  has a different shape.  FIGS. 141-14K  show top views,  FIGS. 14L-140  show side views,  FIGS. 14P-14R  show bottom views, and  FIG. 14S  shows a break out of the alternative embodiment. The organ chamber  104  includes a base  2802 , an organ support surface  2810 , and a removable lid  2820 . 
     For example, the top of the organ chamber can be covered with a single sealable lid  2820 . The removable lid can be hingedly and removably coupled to the organ chamber base member via hinge portions  2832 . The lid is fastened to the base through a series of latches  2836  or other mechanisms. The sealing piece  2818  of the lid can be made of rubber and/or foam, and it can seal the lid to the base to create a fluid or airtight seal. The combination of the lid and base is rigid enough to protect the liver from direct or indirect physical contact. The organ chamber contains orifices (e.g.,  2830 ) for conduit connections for cannulated vessels, including the HA, PV and bile duct. The organ chamber contains a structure  2840  positioned above the measurement drain  2804  that holds the end of the IVC in place during transport of the organ. This structure directs the perfusate exiting from the IVC cannula to the measurement drain. 
     In an alternate embodiment (not shown), the organ chamber  104  can include a double lid system that includes an inner lid and an outer lid. More particularly, in one embodiment, the organ chamber assembly can include a housing, an outer lid and an intermediate lid. The housing can include a bottom and one or more walls for containing the organ. The intermediate lid can cover an opening to the housing for substantially enclosing the organ within the housing, and can include a frame and a flexible membrane suspended within the frame. The flexible membrane can be transparent, opaque, translucent, or substantially transparent. In some embodiments, the flexible membrane includes sufficient excess membrane material to contact an organ contained within the chamber. This feature can enable a medical operator to touch/examine the organ indirectly through the membrane while still maintaining sterility of the system and the organ. For example, the area of the membrane in the intermediate lid can be 100-300% larger than the area defined by the intermediate lid frame or have an area that is 100-300% larger than a two-dimensional area occupied by the liver. In some embodiments, the flexible membrane can be selected so that an operator can perform an ultrasound of the liver through the membrane while maintaining the sterility and/or environment of the chamber. 
     In some embodiments, the intermediate lid can be hinged to the housing. The intermediate lid can also include a latch for securing the intermediate lid closed over the opening of the organ chamber. The outer lid may be similarly hinged and latched or completely removable. In some configurations, gaskets are provided for forming a fluid and/or airtight seal between the intermediate lid frame and the one or more organ chamber walls, and/or for forming a fluid and/or airtight seal between the periphery of the outer lid and the frame of the intermediate lid. In this manner, the environment surrounding the liver  101  can be maintained regardless of whether the outer lid is open. 
     Covering the organ chamber  104  can serve to minimize the exchange of gases between perfusion fluid  108  and ambient air, can help ensure that the oxygen probes measure the desired oxygen values (e.g., values corresponding to perfusate exiting the liver  101 ), and can help maintain sterility. The closing of organ chamber  2204  can also serve to reduce heat loss from the liver. Heat loss can be considerable because of the large surface area of the liver. Heat loss can be an important issue during transport of the liver when the system  600  may be placed into relatively low temperature environments, such as a vehicle, or the outdoors when moving the system  600  into and out of a vehicle. Furthermore, prior to transplantation, system  600  may be temporarily placed in a hospital holding area or in an operating theater, both of which typically have temperatures in the range of 15-22° C. At such ambient temperatures, it is important to reduce heat loss from organ chamber  2204  in order to allow heater  230  to maintain the desired perfusate and liver temperature. Sealing the liver  101  in the organ chamber  2204  can also help to maintain uniformity of the temperature through liver  101 . 
     Referring also to  FIGS. 15A-15D  shows an exemplary embodiment of support surface  2810  that is configured to support the liver  101 . This embodiment includes drainage channels  2812 , drain  2814 , and orifices  2815 . The drainage channels  2812  are configured to channel perfusate draining from the liver  101  and guide it toward the drain  2814 . In some embodiments, when the support surface  2810  is installed in the base  2802 , the drain  2814  is located above and/or in the proximity of measurement drain  2804  thereby ensuring that a substantial amount of the perfusate  108  drains from the support surface  2810  into the measurement drain  2804 . The orifices  2815  are configured to provide supplemental areas for the perfusion to drain from the support surface  2810 . Additionally, the support surface  2810  can be configured to be used with the pad  4500  (described below). The support surface  2810  can also include orifices  2813  that can be used to secure the pad  4500  using, for example, screws or rivets. In some embodiments, when the support surface  2810  is installed in the organ chamber  104 , it is installed so that it rests at approximately a 5-degree angle relative to horizontal, although other angles can be used (e.g., 0-60 degrees). 
     Referring to  FIGS. 16F-16J , in an alternate embodiment, the support surface  4700  is a flexible material that supports and cushions the organ, and support surface  2810  is omitted. The material is of a composition such that is provides a compliant, smooth surface on which the sensitive liver tissue can rest. The surface can be perforated in a manner, e.g., the number, arrangement and diameter of the perforations, to allow for drainage from the liver while providing an atraumatic surface for the liver tissue. In this or other embodiments, the support  4700  is a layer of materials, including a top layer  4706  and a bottom layer  4708  of a compliant material  4706  and an inner layer that is a frame  4702  of malleable metal substrate (e.g., aluminum). In some embodiments, the top layer  4706  and bottom layer  4708  can be made out of polyurethane foam and/or a cellular silicone foam. 
     The assembly is supported by the organ chamber base  2802 , suspending the support surface  4700  above the bottom of the organ chamber base  2802  at an appropriate height to provide displacement by the weight of the organ. The frame  4702  of the support surface  4700  can be held in place to the organ chamber base  2802  through the use of fasteners  4704 , such as molded pins, rivets, screws, or other hardware, that are inserted through openings  4610  in the frame  4702 . 
     In some embodiments, the malleable metal frame  4702  extends into projections  4712 . The projections  4712  may also be enclosed by the top layer  4706  and bottom layer  4708 . The projections  4712  can be formed into positions to surround the liver to stabilize the position of the liver in the x, y and z axes. By bending the projections  4712 , the user can selectively support the liver in a manner that mimics how the liver is supported in the human body. In some embodiments, portions of the frame  4702  can be tapered and terminated with a circle, as shown in  FIG. 16G . The tapering of the portions of the frame  4702  can: i) allow the projections  4712  to be curled more easier and reduce, or even eliminate, the possibility of creasing, and ii) reduce weight of the support surface  4700 . The circle can provide a surface that is easily held by the user. The tapered shape of the portions of the frame  4702  can be specifically selected to facilitate its rolling to conform to a natural arc rather than a fold or bend. The projections  4712  can be of any shape desired to surround the liver. In use, the liver is placed on the top layer  4706  of the support surface  4700 , allowing the support surface  4700  to depress. Then, the projections  4712  may be formed into positions to surround the liver. 
     (ii) Stabilization of Liver 
     In some embodiments, the liver can be stabilized during transport by one or more systems that are designed to support and keep the liver in place without damaging the liver by applying undue pressure thereto. For example, in some embodiments the system  600  can use a soft stabilizing liver pad (e.g.,  4500 ) to support the liver along with a wrap/tarp (e.g.,  4600 ). In some embodiments, the stabilization system can allow some movement of liver up to a predetermined limit (e.g., the system can allow the liver to move up to 2 inches in any direction). In some embodiments the surface on which the liver rests can have a low friction surface, which can also help reduce damage to the liver. The side of the pad in contact with the support surface  2810  can have a high friction surface to help hold the pad in place. 
     The pad can be designed to form a cradle that selectively and controllably supports the liver  101  without applying undue pressure to the liver  101 . That is, were the liver  101  merely placed on the support surface  2810  without anything more, physical damage could result to the portions of the liver on which the liver is resting during transport. For example, the pad can be formed from a material resilient enough to cushion the liver from mechanical vibrations and shocks during transport. 
     An exemplary embodiment of the stabilizing liver pad and wrap is shown as pad  4500  in  FIGS. 16A-16E  and wrap  4600  in  FIG. 16D . The pad  4500  can include two layers: a top layer  4502  and a bottom layer  4504 . In some embodiments, the top layer  4502  can be made out of polyurethane foam and the bottom layer  4504  can be made out of cellular silicone foam. In this embodiment, the top layer  4502  can be 6 mm thick and the bottom layer  4504  can be 3/16″ thick, although other thicknesses and materials can be used. The top layer  4502  and the bottom layer  4504  can be bonded to one another using adhesive such as MOMENTIVE Silicone RTV  118  silicone. The shape of the pad  4500  can be optimized for the liver (e.g., as shown in  FIG. 16A ). For example, the shape of the pad  4500  can include curved corners and one or more fingers (e.g.,  4506 ,  4508 ,  4510 ,  4512 ,  4514 , and  4516 ). The pad  4500  can also include one or more holes  4520  through which the pad  4500  can be secured to the support surface  2810  using, for example, rivets and/or screws. In some embodiments, the pad  4500  can be approximately 16×12 inches in size, although other sizes are possible. 
     Sandwiched between the top layer  4502  and the bottom layer  4504  can be a deformable metal substrate  4518 . The deformable substrate  4518  can be constructed out of a rigid yet pliable material such as metal, although other materials can be used. In some embodiments, the deformable substrate  4518  is aluminum 1100-0 that is 0.04″ thick. The substrate  4518  can be configured so that it is manipulated easily by the user but resists changes to its positioning due to vibration or impact of the liver. The deformable substrate  4518  can include fingers  4522 ,  4524 ,  4526 ,  4528 ,  4530 ,  4532  that correspond to the fingers  4506 ,  4508 ,  4510 ,  4512 ,  4514 ,  4516 , respectively. By bending the various fingers in the pad  4500 , the user can selectively support the liver in a manner that mimics how the liver supported in the human body. An exemplary embodiment of the pad  4500  with the fingers in a curled position is shown in  FIG. 16D . In some embodiments, each of the fingers in the deformable substrate  4518  can be tapered (e.g., as shown by  4534 ) and terminated with a circle. The tapering of the fingers in the substrate  4518  can i) allow the fingers to be curled easier and reduce, or even eliminate the possibility of the finger creasing while being bent, and ii) reduce weight of the pad  4500 . The circle can provide a surface that is easily held by the user. The tapered shape of the fingers can be specifically selected to facilitate a rolling of the pad finger to conform to a natural arc rather than a fold or bend. 
     Referring to  FIGS. 16F-16J , in an alternate embodiment, the stabilizer may be comprised of three layers. The top layer  4706  and the bottom layer  4708  may be made of cellular silicone foam. Each foam layer can be 3/16″ thick, although other thicknesses and materials can be used. The inner layer is a frame  4702  of a deformable metal substrate in the form of a narrow frame. The frame  4702  can be constructed out of a rigid yet pliable material such as metal, although other materials can be used. In some embodiments, the frame  4702  is aluminum 1100-0 that is 0.04″ thick. The frame  4702  can be configured so that it is manipulated easily by the user, but resists changes to its positioning due to vibration or impact of the liver. 
     The top layer  4706  and the bottom layer  4708  can be bonded to one another and to the frame  4702  using adhesive such as MOMENTIVE Silicone RTV  118  silicone. The top and bottom layers  4706 ,  4708  cover the area inside the frame  4702 , thereby creating a compliant support surface  4700  on which the liver is located for transport. The shape of the support surface  4700  can be optimized for the liver. For example, the shape of the support surface  4700  can include curved corners and one or more projections  4712  to constrain the movement of the liver during transport. In some embodiments, a wrap  4600  can be placed over the liver to hold it in place during transport and maintain moisture in the liver. For example, as shown in  FIG. 16D , the wrap  4600  can be attached to the pad on one side (e.g., the right side in  FIG. 16D ) and the remaining portion of the wrap can be draped over the liver. In other embodiments, the wrap can be secured on multiple edges or all edges. The wrap  4600  may also be used with flexible support surface  4700 . In some embodiments, the wrap can perform one or more functions such as securing the liver during transplant, helping maintain sterility, and preserving the moisture in the liver by acting as a vapor barrier. The wrap can be made out of a polyurethane sheet and can be opaque or clear to facilitate visual inspection of the liver. The size of the wrap  4600  can vary. For example, it can have a length that is between 0.5 and 24 inches and a width that is between 0.5 and 24 inches. 
     2. General Description of Perfusion Circuit 
     As described above, the liver has two blood supply sources: the hepatic artery and the portal vein, which provide approximately ⅓ and ⅔ of the blood supply to the liver, respectively. Typically, when comparing the blood supply provided by the hepatic artery and the portal vein, the hepatic artery provides a blood supply with a higher pressure yet low flow rate and the portal vein provides a blood supply with a lower-pressure yet high flow rate. Also, typically, the hepatic artery provides a pulsatile flow of blood to the liver whereas the portal vein does not. 
     The system  600  can be configured to supply perfusion solution to the liver in a manner that simulates the human body (e.g., the proper pressures, volumes, and pulsatile flows) using a single pump. For example, in a normal flow mode, the system  600  can circulate the perfusion fluid to the liver in the same manner as blood would circulate in the human body. More particularly, the perfusion fluid enters the liver through the hepatic artery and the portal vein and flows away from the liver via the IVC. In normal flow mode, the system  100  pumps the perfusion fluid to the liver  102  at a near physiological rate of between about 1-3 L/min, although in some embodiments the range can be 1.1-1.75 L/min (although the system can also be configured to provide flow rates outside of this range, e.g., 0-10 L/min). Each of the foregoing numbers is the total flow per minute provided to the hepatic artery and portal vein. 
     Referring to  FIG. 17 , an exemplary embodiment of a perfusion set  100  is shown. The perfusion set  100  can include a reservoir  160 , a one-way valve  191 , a pump  106 , a one-way valve  310 , compliance chambers  184 ,  186 , a gas exchanger  114 , a heater  110 , flow meters  136 ,  138   a ,  138   b , a divider  105 , a flow clamp  190  pressure sensors  130   a ,  130   b , organ chamber  104 , a sensor  140 , defoamer/filter  161 , and tubing/interfaces to connect the same. The liver can also be connected to a bag  187  the collects bile produced therefrom. In some embodiments, the perfusion set  100  is contained entirely within the single use module  634 , although this is not required. In some embodiments, the inferior vena cava (IVC) is cannulated so that flow from the IVC can be directed to a conduit in which the IVC pressure, flow, and oxygen saturation can be measured. In other embodiments, the IVC is not cannulated and perfusate flows freely from the IVC into the organ chamber  104  (and ultimately into the drain(s) in the organ chamber  104 ). 
     In one embodiment, perfusion fluid flows from the reservoir  160  to valve  191  and then to the pump  106 . After pump  106 , the perfusion can flow to one-way valve  310  to compliance chamber  184 . After compliance chamber  184 , the perfusion fluid can flow to the gas exchanger  114  and on to the heater  110 . After the heater  110  the perfusion fluid can flow to the flow meter  136  which is configured to measure the flow rate at that part of the perfusion circuit. After the flow meter  136  the perfusion fluid flows to the divider  105 , which can divide the flow of the perfusion fluid into branches  313  and  315 . In some embodiments, the divider  105  can split the flow between the hepatic artery and the portal vein at a ratio of between 1:2 and 1:3. Branch  313  is ultimately provided to the portal vein of the liver whereas branch  315  is ultimately provided to the hepatic artery of the liver. The branch  313  can include flow meter  138   a  and the compliance chamber  186  which provides perfusion fluid to the flow clamp  190 . From the flow clamp  190  the perfusion fluid can flow to the pressure sensor  130   a  before being provided to the portal vein of the liver. The branch  315  can include a flow meter  138   b  which provides perfusion fluid to the pressure meter  130   b  before being provided to the hepatic artery of the liver. After perfusion fluid exits the liver, some of the perfusion fluid is collected by the measurement drain  2804  and the remainder is collected by the main drain  2806 . The perfusion fluid collected by the measurement drain  2804  can be provided to the sensor  140 . Perfusion fluid exiting the sensor  140  can be provided to the defoamer/filter  161 . The perfusion fluid collected by the drain  2806  can be provided directly to the defoamer/filter  161 . Perfusion fluid exiting the defoamer/filter  161  can be provided to the reservoir  160 . Additionally, bile produced by the liver can be collected in a bag  187 . 
     In some embodiments, the system  100  has at least 1.6 L of perfusion fluid (or other fluid) in it when operating. 
     3. Reservoir 
     The single use module  634  can include a perfusate reservoir  160  that is mounted below the organ chamber  104 . The reservoir  160  can be configured to store and filter perfusion fluid  108  as it circulates through the perfusion set  100 . Reservoir  160  can include one or more one-way valves (not shown) that prevent the flow of perfusion fluid in the wrong direction. In some embodiments, the reservoir  160  has a minimum capacity of 2 L, although smaller capacities can be used. In some embodiments, the reservoir  160  can include a filter (shown separately in  FIG. 17  as defoamer/filter  161 ) that is designed to trap particles in the perfusion fluid  108 . In some embodiments, the filter is configured to trap particles in the perfusion fluid  108  that are greater than 20 microns. In some embodiments, the reservoir  160  includes a defoamer (shown separately in  FIG. 17  as defoamer/filter  161 ) that reduces and/or eliminates foam generated from the perfusion fluid  108 . In some embodiments, the reservoir  160  can be made of a clear material and can include level markings so that a user may estimate the volume of the perfusion fluid in the reservoir  160 . In some embodiments, the reservoir  160  can be configured to allow for a minimum of 4.5 L per minute a fluid ingress from the organ chamber  104 , although other flow rates are possible. In some embodiments, the reservoir  160  includes a vent to the atmosphere that includes a sterile barrier (not shown). 
     The reservoir  160  can be positioned within the system  600  in various locations. For example, the reservoir  160  can be located above the liver, completely below the liver, partially below the liver, next to the liver, etc. Thus, one potential benefit some embodiments described herein is that the reservoir can be positioned below the liver since a gravity-induced pressure head in the perfusion fluid is not required. 
     4. Valves 
     In some embodiments, the valves  191  and  310  are one-way valves configured to ensure that the perfusion fluid in the system  100  flows in the correct direction through the system  100 . Exemplary embodiments of the valves  191  and  310  are described above with respect to the pump  106 . 
     5. Perfusion Fluid Pump 
     An exemplary embodiment of the pump  106  is described more fully above with respect to  FIGS. 6A-6E . As described above, in some embodiments, the pump is split between the multiple use module  650  and the single use module  634 . For example, the single use module  634  can include the pump interface assembly while the multiple use module  650  includes the pump driver portion. 
     6. Compliance Chamber 
     While the pump  106  provides a generally pulsatile output, the characteristics of that flow are typically adapted to match the flow typically provided by the human body to the liver. For example, the portal vein typically does not provide a pulsatile flow of blood to a liver when the liver is in vivo. Thus, in some embodiments, in order to provide a non-pulsatile flow of perfusion fluid to the portal vein of the liver, one or more compliance chambers can be used to mitigate the pulsatile flow generated by the pump  106 . In some embodiments, the compliance chambers are essentially small in-line fluid accumulators with flexible, resilient walls for simulating the human body&#39;s vascular compliance. The compliance chambers can aid the system  600  by more accurately mimicking blood flow in the human body, for example, by filtering/reducing fluid pressure spikes due, for example, to the flow profile from the pump  106 . In the embodiment of system  600  described herein, two compliance chambers are used: compliance chamber  184  and  186 . Various characteristics of the compliance chambers can be varied to achieve the desired result. For example, the combination i) a pressure versus volume relationship, and ii) the overall volume of the compliance chamber can affect the performance of the compliance chamber. Preferably the characteristics of the respective compliance chambers are chosen to achieve the desired effect. 
     In some embodiments, the compliance chamber  184  is located between the valve  310  and the gas exchanger  114  and operates to partially smooth the pulsatile output of the pump  106 . For example, the compliance chamber  184  can be configured such that the flow of perfusion fluid ultimately provided to the hepatic artery of the liver mimics that of the human body. In some embodiments, the compliance chamber  184  can be omitted if the output of the pump  106  results in a perfusate flow to the hepatic artery that closely mimics that of the human body. 
     In some embodiments, the compliance chamber  186  is located between the divider  105  and the flow clamp  190 . The compliance chamber  186  can operate to substantially reduce, or even eliminate the pulsatile nature of the flow of perfusion fluid ultimately provided to the portal vein. Additionally, while the compliance chamber  186  is positioned before the flow clamp  190  in the branch  313 , this is not required. For example, flow clamp  190  can come before the compliance chamber  186 . In this embodiment, however, it may be desirable to adjust the parameters of the compliance chamber  186 . 
     7. Gas Exchanger 
     The system  600  can also include a gas exchanger  114  (also referred to herein as an oxygenator) that is configured to, for example, remove CO 2  from the perfusion fluid and add 02. The gas exchanger  114  can receive input gas from an external or onboard source (e.g., gas supply  172  or oxygen concentrator) through a gas regulator and/or a gas flow chamber which can be a pulse-width modulated solenoid valve that controls gas flow, or any other gas control device that allows for precise control of gas flow rate. In some embodiments, the gas exchanger  114  is a standard membrane oxygenator, such as the interventional lung assist membrane ventilator from NOVALUNG or member of the Quadrox series from Maquet of Wayne, N.J. In the illustrative embodiment, the gas can be a blend of oxygen, carbon dioxide, and nitrogen. An exemplary blend of gas is: 80% 02, 0.1% CO 2 , and the balance N 2  with a blend process accuracy of 0.030%. In some embodiments, the operation of the gas exchanger, regulator, and/or gas flow chamber can be controlled by the controller  150  using the output of the sensor  140 . 
     In some embodiments, the oxygenator  114  can have an oxygen transfer rate of 27.5 mLpm/LPM minute at a blood flow of 500 mLpm at standard conditions. The oxygenator  114  can also have a carbon dioxide transfer rate of 20 mLpm at a blood flow rate of 500 mLpm at standard conditions. Standard conditions can be, for example: gas=100% O 2 , blood temp=37.0±0.5° C., hemoglobin=12±1 mg %, SvO 2 =65±5%, pCO2=45±5 mmHg, and gas to blood ratio of 1:1). The above values are exemplary only and not limiting. Transfer rates higher and/or lower than the rate identified above can be used. 
     8. Heater/Cooler 
     The perfusion set  100  can include one or more heaters that are configured to maintain the temperature of the perfusion fluid  108  at a desired level. By warming the perfusion fluid, and the flowing the warmed liquid through the liver, the liver itself can also be warmed. While the heater can be capable of warming the perfusion fluid to a wide range of temperatures (e.g., 0-50° C.), typically, the heater warms the perfusion fluid to a temperature of 30-37° C. In some more specific embodiments, the heater can be configured warm the perfusion fluid to a temperature of 34-37° C., 35-37° C., or any other range that falls within 0-50° C. In some embodiments, the ranges described herein can also extend to 42° C. 
     Referring to  FIGS. 18A-18G , an exemplary embodiment of a heater assembly  110  is shown.  FIGS. 18A-18F  depict various views of the perfusion fluid heater assembly  110 . The heater assembly  110  can include a housing  234  having an inlet  110   a  and an outlet  110   b . As shown in both the longitudinal cross-sectional and the lateral cross-sectional views, the heater assembly  110  can include a flow channel  240  extending between the inlet  110   a  and the outlet  110   b . The heater assembly  110  can be conceptualized as having upper  236  and lower  238  symmetrical halves. Accordingly, only the upper half is shown in an exploded view in  FIG. 18F . 
     The flow channel  240  can be formed between first  242  and second  244  flow channel plates. The inlet  110   a  can flow the perfusion fluid into the flow channel  240  and the outlet  110   b  can flow the perfusion fluid out of the heater  110 . The first  242  and second  244  flow channel plates can have substantially bioinert perfusion fluid  108  contacting surfaces for providing direct contact with the perfusion fluid flowing through the channel  240 . The fluid contacting surfaces can be formed from a treatment or coating on the plate or may be the plate surface itself. The heater assembly  110  can include first and second electric heaters  246  and  248 , respectively. The first heater  246  can be located adjacent to and can couple heat to a first heater plate  250 . The first heater plate  250 , in turn, can couple the heat to the first flow channel plate  242 . Similarly, the second heater  248  can be located adjacent to and can couple heat to a second heater plate  252 . The second heater plate  252  can couple the heat to the second flow channel plate  244 . According to the illustrative embodiment, the first  250  and second  252  heater plates can be formed from a material, such as aluminum, that conducts and distributes heat from the first  246  and second  248  electric heaters, respectively, relatively uniformly. The uniform heat distribution of the heater plates  250  and  252  can enable the flow channel plates to be formed from a bioinert material, such as titanium, reducing concern regarding its heat distribution characteristic. The heater assembly  110  can also include O-rings  254  and  256  for fluid sealing respective flow channel plates  242  and  244  to the housing  234  to form the flow channel  240 . In some embodiments the function of the heater plate and flow channel plate are combined in a single plate. 
     The heater assembly  110  can further include first assembly brackets  258  and  260 . The assembly bracket  258  can mount on the top side  236  of the heater assembly  110  over a periphery of the electric heater  246  to sandwich the heater  246 , the heater plate  250  and the flow channel plate  242  between the assembly bracket  258  and the housing  234 . The bolts  262   a - 262   j  can fit through corresponding through holes in the bracket  258 , electric heater  246 , heater plate  250  and flow channel plate  242 , and thread into corresponding nuts  264   a - 264   j  to affix all of those components to the housing  234 . The assembly bracket  260  can mount on the bottom side  238  of the heater assembly  110  in a similar fashion to affix the heater  248 , the heater plate  252  and the flow channel plate  244  to the housing  234 . A resilient pad  268  can interfit within a periphery of the bracket  258 . Similarly, a resilient pad  270  can interfit within a periphery of the bracket  260 . A bracket  272  can fit over the pad  268 . The bolts  278   a - 278   f  can interfit through the holes  276   a - 276   f , respectively, in the bracket  272  and thread into the nuts  280   a - 280   f  to compress the resilient pad  268  against the heater  246  to provide a more efficient heat transfer to the heater plate  250 . The resilient pad  270  can be compressed against the heater  248  in a similar fashion by the bracket  274 . 
     The illustrative heater assembly  110  can include temperature sensors  120  and  122  and dual-sensor  124 . The dual sensor  124 , which in practice can include a dual thermistor sensor for providing fault tolerance, can measure the temperature of the perfusion fluid  108  exiting the heater assembly  110 , and can provide these temperatures to the controller  150 . As described in further detail with respect to the heating subsystem  149 , the signals from the sensors  120 ,  122  and  124  can be employed in a feedback loop to control drive signals to the first  246  and/or second  248  heaters to control the temperature of the heaters  256  and  248 . Additionally, to ensure that heater plates  250  and  252  and, therefore, the blood contacting surfaces  242  and  244  of the heater plates  250  and  252  do not reach a temperature that might damage the perfusion fluid, the illustrative heater assembly  110  can also include temperature sensors/lead wires  120  and  122  for monitoring the temperature of the heaters  246  and  248 , respectively, and providing these temperatures to the controller  150 . In practice, the sensors attached to sensors/lead wires  120  and  122  can be RTD (resistance temperature device) based. The signals from the sensors attached to sensors/lead wires  120  and  122  can be employed in a feedback loop to further control the drive signals to the first  246  and/or second  248  heaters to limit the maximum temperature of the heater plates  250  and  252 . As a fault protection, there can be sensors for each of the heaters  246  and  248 , so that if one should fail, the system can continue to operate with the temperature at the other sensor. 
     The heater  246  of the heater assembly  110  can receive from the controller  150  drive signals  281   a  and  281   b  (collectively  281 ) onto corresponding drive lead  282   a . Similarly, the heater  248  receives from the controller  150  drive signals  283   a  and  283   b  (collectively  283 ) onto drive lead  282   b . The drive signals  281  and  283  control the current to, and thus the heat generated by, the respective heaters  246  and  248 . More particularly, as shown in  FIG. 18G , the drive leads  282   a  includes a high and a low pair, which connect across a resistive element  286  of the heater  246 . The greater the current provided through the resistive element  286 , the hotter the resistive element  286  gets. The heater  248  operates in the same fashion with regard to the drive lead  282   b . According to the illustrative embodiments, the element  286  has a resistance of about 5 ohms. However, in other illustrative embodiments, the element may have a resistance of between about 3 ohms and about 10 ohms. The heaters  246  and  248  can be controlled independently by the processor  150 . 
     The heater assembly  110  housing components can be formed from a molded plastic, for example, polycarbonate, and can weigh less than about one pound. More particularly, the housing  234  and the brackets  258 ,  260 ,  272  and  274  can all be formed from a molded plastic, for example, polycarbonate. According to another feature, the heater assembly can be a single use disposable assembly. 
     In operation, the illustrative heater assembly  110  can use between about 1 Watt and about 200 Watts of power, and can be sized and shaped to transition perfusion fluid  108  flowing through the channel  240  at a rate of between about 300 ml/min and about 5 L/min from a temperature of less than about 30° C. to a temperature of at least 37° C. in less than about 30 minutes, less than 25 minutes, less than about 20 minutes, less than about 15 minutes, or even less than about 10 minutes, without substantially causing hemolysis of cells, or denaturing proteins or otherwise damaging any blood product portions of the perfusion fluid. 
     The heater assembly  110  can include housing components, such as the housing  234  and the brackets  258 ,  260 ,  272  and  274 , that are formed from a polycarbonate and weighs less than about 5 lb. In some embodiments, the heater assembly can weigh less than 4 pounds. In the illustrative embodiment, the heater assembly  110  can have a length  288  of about 6.6 inches, not including the inlet  110   a  and outlet  110   b  ports, and a width  290  of about 2.7 inches. The heater assembly  110  can have a height  292  of about 2.6 inches. The flow channel  240  of the heater assembly  110  can have a nominal width  296  of about 1.5 inches, a nominal length  294  of about 3.5 inches, and a nominal height  298  of about 0.070 inches. The height  298  and width  296  can be selected to provide for uniform heating of the perfusion fluid  108  as it passes through the channel  240 . The height  298  and width  296  are also selected to provide a cross-sectional area within the channel  240  that is approximately equal to the inside cross-sectional area of fluid conduits that carry the perfusion fluid  108  into and/or away from the heater assembly  110 . In one embodiment, the height  298  and width  296  are selected to provide a cross-sectional area within the channel  240  that is approximately equal to the inside cross-sectional area of the inlet fluid conduit  792  and/or substantially equal to the inside cross-sectional area of the outlet fluid conduit  794 . 
     Projections  257   a - 257   d  and  259   a - 259   d  can be included in the heater assembly  110  and can be used to receive a heat-activated adhesive for binding the heating assembly to the multiple-use unit  650 . 
     In addition to the heater  110 , the system  100  can also include an additional heater (not shown) that is placed inside the organ chamber  110  to provide heat (e.g., a resistance heater). 
     9. Pressure/Flow Probes 
     In some embodiments, the system  600  can include pressure sensors  130   a ,  130   b  and flow sensors  138   a ,  138   b . The probes and/or sensors can be obtained from standard commercial sources. For example, the flow rate sensors  136 ,  138   a , and  138   b  can be ultrasonic flow sensors, such as those available from Transonic Systems Inc., Ithaca, N.Y. The fluid pressure probes  130   a ,  130   b  can be conventional, strain gauge pressure sensors available from MSI or G.E. Thermometrics. Alternatively, a pre-calibrated pressure transducer chip can be embedded into organ chamber connectors and connected to the controller  150 . In some embodiments, the sensors can be configured to measure mean, instantaneous, and/or peak values flow/pressure values. In embodiments where a mean value is calculated, the system can be configured to calculate the mean pressure using a running average sampled values. The sensors can also be configured to provide systolic and diastolic measurements. While these are shown as separate devices in  FIG. 17 , in some embodiments, a single device can measure both pressure and flow. In some embodiments, the sensors can be configured to measure pressures between 0-225 mmHg with an accuracy of ±(7%+10 mmHg) for each transducer. In some embodiments the flow sensor can be configured to measure flow rates between 0-10 L/min with an accuracy of ±12%+0.140 L/min. In some embodiments the pressure and flow sensors can be configured to sample the pressure/flow within the cannula tip, within the vessel, or in the tubing prior to the cannula. 
     While there is a single sensor  130   b  and a single sensor  130   a , these sensors can include more than one pressure sensor. For example, in some embodiments, the sensor  130   a  can include two pressure sensors for redundancy. In such an embodiment, when both sensors are working the controller  150  can average the output of both to determine the actual pressure. In embodiments where one of the two pressure sensors in sensor  130   a  fails, the controller can ignore the malfunctioning sensor. 
     As described more fully below with respect to  FIGS. 23A-23K , the pressure sensors can be contained in a housing  3010  of the connector  3000  (and similarly on the connector  3050 ). 
     10. Flow Control 
     The system  600  can be configured to provide perfusate flow rates varying from 0-10 L/min at the flow sensor  136  (e.g., before the divider  105 ). In some embodiments, the system can be configured to provide a flow rate of 0.6-4 L/min at the flow sensor  136 , or even more specifically, 1.1-1.75 L/min at the flow sensor  136 . These ranges are exemplary only and the flow rate at the sensor  136  can be provided within any range that falls within 0-10 L/min. The system  600  can be configured to provide perfusate flow rates varying from 0-10 L/min, and more specifically 0.25-1 L/min to the hepatic artery of the liver (e.g., as measured by the flow sensor  130   b ). These ranges are exemplary only and the flow rate at hepatic artery can be provided within any range that falls within 0-10 L/min. The system  600  can be configured to provide perfusate flow rates varying from 0-10 L/min, and more specifically 0.75 to 2 L/min to the portal vein of the liver (e.g., as measured by the flow sensor  130   a ). These ranges are exemplary only and the flow rate at the portal vein can be provided within any range that falls within 0-10 L/min. 
     In some embodiments, the system  100  can be capable of generating perfusate flow through the perfusion module at rates of 0.3-3.5 L/min with at least 1.8 Liters of perfusion fluid therein. In some embodiments, the pressure provided to the hepatic artery via the branch  315  can be between 25-150 mmHg and more specifically between 50-120 mmHg, and the pressure provided to the portal vein via the branch  313  can be between 1-25 mmHg and more specifically 5-15 mmHg. These ranges are exemplary only and the respective pressures can be provided within any range that falls within 5-150 mmHg. 
     11. Perfusate Sensors 
     The sensor  140  can sense one or more characteristics of the perfusion fluid flowing from the liver by measuring the amount of light absorbed or reflected by the perfusion fluid  108  when applied at multi-wavelengths. For example, the sensor  140  can be an O 2  saturation, hematocrit, and/or temperature sensor.  FIGS. 19A-19C  depict an exemplary embodiment of the sensor  140 . The sensor  140  can include an in-line cuvette shaped section of tube  812  connected to the conduit  798 , which can have at least one optically clear window through which an infrared sensor can provide infrared light. Exemplary embodiments of the sensor  140  can be the BLOP4 and/or BLOP4 Plus probes from DATAMED SRL. The cuvette  812  can be a one-piece molded part having connectors  801   a  and  801   b . The connectors  801   a  and  801   b  can be configured to adjoin to connecting receptacles  803   a  and  803   b , respectively, of conduit ends  798   a  and  798   b . This interconnection between cuvette  812  and conduit ends  798   a  and  798   b  can be configured so as to provide a substantially constant cross-sectional flow area inside conduit  798  and cuvette  812 . The configuration can thereby reduce, and in some embodiments substantially removes, discontinuities at the interfaces  814   a  and  814   b  between the cuvette  812  and the conduit  798 . Reduction/removal of the discontinuities can enable the blood based perfusion fluid  108  to flow through the cuvette with reduced lysing of red blood cells and reduced turbulence, which can enable a more accurate reading of perfusion fluid oxygen levels. This can also reduce damage to the perfusion fluid  108  by the system  600 , which can ultimately reduce damage done to the organ being transplanted. 
     The cuvette  812  can be formed from a light transmissive material, such as any suitable light transmissive glass or polymer. As shown in  FIG. 19A , the sensor  140  can also include an optical transceiver  816  for directing light waves at perfusion fluid  108  passing through the cuvette  812  and for measuring light transmission and/or light reflectance to determine the amount of oxygen in the perfusion fluid  108 . In some embodiments a light transmitter can be located on one side of the cuvette  812  and a detector for measuring light transmission through the perfusion fluid  108  can be located on an opposite side of the cuvette  812 .  FIG. 19C  depicts a top cross-sectional view of the cuvette  812  and the transceiver  816 . The transceiver  816  can fit around cuvette  812  such that transceiver interior flat surfaces  811  and  813  mate against cuvette flat surfaces  821  and  823 , respectively, while the interior convex surface  815  of transceiver  816  mates with the cuvette  812  convex surface  819 . In operation, when UV light is transmitted from the transceiver  816 , it travels from flat surface  811  through the fluid  108  inside cuvette  812 , and is received by flat surface  813 . The flat surface  813  can be configured with a detector for measuring the light transmission through the fluid  108 . 
     In some embodiments, the sensor  140  can be configured to measure SvO 2  in the range of 0-99%, although in some embodiments this can be limited to 50-99%. To the extent that the sensor  140  also measures hematocrit, the measurement range can be from 0-99%, although in some embodiments this can be limited to 15-50%. In some embodiments, the accuracy of the measurements made by the sensor  140  can be ±5 units and measurements can occur at least once every 10 seconds. In embodiments of the sensor  140  that also measure temperature, the measurement range can be from 0-50° C. 
     In some embodiments, the system  600  can also include one or more lactate sensors (not shown) that are configured to measure lactate in the perfusion fluid. For example, a lactate sensor can be placed between the measurement drain  2804  and the defoamer/filter  161 , in branch  315 , and/or in branch  313 . In this configuration, the system  600  can be configured to measure lactate values of the perfusion fluid before and/or after processing by the liver. In some embodiments, the lactate sensor can be an in-line lactate analyzer probe. In some embodiments the lactate sensor can also be external to the system  600  and use samples of the perfusion fluid withdrawn from a sampling port. 
     In some embodiments the system  600  can also include one or more sensors (e.g., the sensor  140  and/or other sensors such as a disposable blood gas analysis probe) to measure pH, HCO3, pO2, pCO2, glucose, sodium, potassium, and/or lactate. Exemplary sensors that can be used to measure the foregoing values include off-the-shelf probes made by Sphere Medical of Cambridge, United Kingdom. As described above, the sensor can be coupled to the measurement drain  2804 . Alternatively, a piece of tubing can be used to route perfusion fluid to/from the sensor. Some embodiments of the sensor use calibration fluid before and/or after performing a measurement. In embodiments using such sensors, the system can include a valve that can be used to control the flow of calibration fluid to the sensor. In some embodiments, the valve can be manually actuated and/or automatically actuated by the controller  150 . In some embodiments of the sensor, calibration fluid is not used, which can result in a continuous sampling of the perfusion fluid. 
     In addition to using the foregoing sensors in a feedback loop to control the system  600 , some or all of the sensors can also be used to determine the viability of the liver for transplant. 
     In some embodiments, external blood analyzer sensors can also be used. In these embodiments, blood samples can be drawn from ports in the branches  313 ,  315  (the ports are described more fully below). The blood samples can be provided for analysis using standard hospital equipment (e.g., radiometer) or via point of care blood gas analysis (e.g., I-STAT1 from Abbott Laboratories or the Epoc from Alere). 
     12. Sampling/Infusion Ports 
     The system  600  can include one or more ports that can be used to sample the perfusion fluid and/or infuse fluid into the perfusion fluid. In some embodiments, the ports can be configured to work with standard syringes and/or can be configured with controllable valves. In some embodiments, the ports can be luer ports. Essentially, the system  100  can include infusion/sampling ports at any location therein and the following examples are not limiting. 
     Referring to  FIG. 17 , the system  100  can include ports  4301 ,  4302 ,  4303 ,  4304 ,  4305 ,  4306 ,  4307 , and  4308 . The port  4301  can be used to provide a bolus injection and/or flush (e.g., a post-preservation flush) to the hepatic artery. The port  4302  can be used to provide a bolus injection and/or flush (e.g., post-preservation flush) to the portal vein. The ports  4303 ,  4304 ,  4305  can be coupled to the respective channels of the solution pump  631  and can provide infusion to the portal vein (in the case of  4303  and  4304 ) and to the hepatic artery (in the case of  4305 ). The ports  4306  and  4307  can be used to obtain a sample of the perfusion fluid flowing into the hepatic artery and portal vein, respectively. The port  4308  can be used to sample the perfusion fluid in the IVC (or hepatic veins, depending on how the liver was harvested). In some embodiments, each of the ports can include a valve that the user operates to obtain a flow from the ports. 
     The port configuration shown in  FIG. 17  is exemplary, and more or fewer ports can be used. Additionally, ports can be located in additional locations such as between the pump  106  and the divider  105 , between the organ chamber and bile bag  187 , in the bile bag  187 , between the main drain  2806  and the defoamer/filter  161 . 
     The single use module  634  can also include a tube  774  for loading priming solution and the exsanguinated blood from the donor or blood products from a blood bank into the reservoir  160 . The priming tube  774  can be provided directly to the reservoir  160  and/or it can be located so that an end of it empties directly above the drain  2806  in the organ chamber  104 . The single use module  634  can also include non-vented caps for replacing vented caps on selected fluid ports that are used, for example, while running a sterilization gas through the single use module  634 . 
     Some embodiments the system  100  can also include vents and/or air purge ports to eliminate air from the hepatic artery interface, the portal vein interface, or elsewhere in the system  100 . 
     In some embodiments an extra infusion port can be included for the user to provide an imaging contrast medium to the perfusion fluid so that imaging of the liver can be enhanced. For example, an ultrasound contrast medium can be infused to perform a contrast-enhanced ultrasound. 
     13. Organ Assist 
     While perfusion fluid can drain naturally from the liver as a result of the pressure applied to the hepatic artery and portal vein, the system  600  can also include additional features that help the perfusion fluid drain from the liver in a manner that mimics the human body. That is, in the human body the diaphragm typically applies pressure to the liver as the person breathes. This pressure can help expel blood from the person&#39;s liver. The system  600  can include one or more systems that are designed to mimic the pressure applied by the diaphragm to the liver. Exemplary embodiments include contact and contactless embodiments. In some embodiments, the amount of pressure applied to the liver can be less than the pressure in the portal vein and/or hepatic artery of the liver. Sketches of exemplary embodiments of the organ assist systems are shown in  FIG. 30 . 
     One embodiment of a contactless pressure system is a system that varies the air pressure in the organ chamber  104  to simulate pressure applied by the diaphragm to the liver. In this embodiment, the organ chamber  104  can be configured to provide a substantially airtight environment such that the air pressure inside the organ chamber  104  can be maintained at an elevated (or lowered) state when compared to the outside atmosphere. As the air pressure in the organ chamber  104  rises, it can apply pressure to the liver that simulates the pressure applied by the diaphragm thereby increasing the rate at which the liver expels perfusion fluid. In some embodiments, the air pressure can be varied in a manner that mimics a human breathing rate (e.g., 12-15 times per minute), or at other rates (e.g., 0.5 to 50 times per minute). The air pressure in the organ chamber  104  can be varied by various methods including, for example, a dedicated air pump (not shown) and/or the onboard gas supply  172 . In some embodiments, the air pressure inside the organ chamber  104  can be controlled by the controller  150 . In these embodiments, the controller can also be coupled to an air pressure sensor measuring the pressure inside the organ chamber  104  that is used as part of a feedback control loop. 
     One embodiment of a contact pressure system is a system that that uses a wrap and/or bladder to apply pressure to the liver. For example, a wrap can be placed over some or all of the liver within the organ chamber  104 . The edges of the wrap can then be mechanically tightened to apply pressure to the portion of the liver covered by the wrap. In this example, one or more small motors attached to various points around the periphery of the wrap can be used to tighten the edges of the wrap. In another example of a contact pressure system, a removable bladder can be used (not shown). In this embodiment, an inflatable bladder can be placed between the liver and the top surface (or some other portion) of the organ chamber  104 . A pump can then be used to inflate/deflate the bladder. As the bladder inflates, it can press against the top surface (or other portion) of the organ chamber  104  thereby exerting pressure on the liver contained therein. As with the contactless system described above, the pressure applied to the liver can be applied periodically to mimic the natural pressure provided by the diaphragm. In some embodiments, the pressure applied to the liver can be varied in a manner that mimics human breathing rate (e.g., 12-15 times per minute), or at other rates (e.g., 0.5 to 50 times per minute). Regardless of whether the pressure is applied to the liver using a wrap or a bladder, the pressure can be controlled by the controller  150 . In some embodiments, one or more sensors that measure the pressure applied to the liver can be included in the organ chamber  104  as part of a feedback control loop. Other methods of providing contact pressure to the liver are also possible. 
     14. Cannulation 
     Operationally, in one embodiment, a liver can be harvested from a donor and coupled to the system  600  by a process of cannulation. For example, interface  162  can be cannulated to vascular tissue of the hepatic artery via a conduit located within the organ chamber assembly. Interface  166  can be cannulated to vascular tissue of the portal vein via a conduit located within the organ chamber assembly. The liver emits the perfusate through the inferior vena cava (IVC). In some embodiments, the IVC can be cannulated by interface  170  (not shown) so that the flow can be directed to a conduit in which the IVC pressure, flow and oxygen saturation can be measured. In another embodiment, the IVC can be cannulated by the interface  170  to direct the flow within the organ chamber. In still another embodiment, the IVC is not cannulated and the organ chamber provides a means to direct the perfusate flow for efficient collection to the reservoir. 
     Each of the interfaces  162 ,  166  and  170  can be cannulated to the liver by pulling vascular tissue over the end of the interface, then tying or otherwise securing the tissue to the interface. The vascular tissue is preferably a short segment of a blood vessel that remains connected to the liver after the liver is severed and explanted from the donor. In some embodiments, the short vessel segments can be 0.25-5 inches, although other lengths are possible. 
     Referring to  FIGS. 21A-21D , an exemplary embodiment of a hepatic artery cannula  2600  is shown. The cannula  2600  is generally tubular in shape and includes a first portion  2604  that is configured to be inserted into tubing used in the system  100  and includes a first orifice  2612 . The first portion  2604  can also include a ring  2602  that can be used to help secure the first portion  2604  inside of the tubing of the system  100  by friction. The cannula  2600  can also include a second portion  2608  that can have a smaller diameter than the first portion  2604  and that forms a second orifice  2614 . The second portion  2608  can also include a channel  2610  that is recessed from the surface of the second portion  2608 . In some embodiments, when the user ties the hepatic artery to the second portion  2608 , the user can place the suture in the channel  2610  to help secure the hepatic artery. Between the first and second portions can be a collar  2606 . The outside diameter of the collar can have a slightly larger diameter than the first portion  2604  to prevent the tubing of the system  100  from extending over the second portion  2608  when inserted. Viewing the cross-section shown in  FIG. 21D , the inside diameter of the cannula  2600  can vary, with a taper  2616  therebetween. The cannula  2600  can be formed in various sizes, lengths, inside diameters, and outside diameters. In some embodiments of the system  600 , it can be advantageous to have a substantially large inside diameter in the first portion  2604  and a much smaller inside diameter in the second portion  2608  to offset pressure and flow changes caused by the cannula  2600 . 
     Referring to  FIGS. 21H-21K , in an alternative embodiment the cannula  2600  has a beveled cut end  2618 . 
     The outside diameter of the first portion  2604  can be configured to be press-fit inside of silicone or polyurethane tubing. Thus, while the outside diameter of the first portion  2604  can vary, one exemplary range of possible diameters is 0.280-0.380″. The outside diameter of the second portion  2608  can range between 4-50 Fr, but more specifically between 12-20 Fr. Additionally, the cannula  2600  can be made from various biocompatible materials, such as stainless steel, titanium, and/or plastic (the dimensions of the cannula  2600  can be adapted to be manufacturable using different materials). 
     Additionally 10-20% of the population have a genetic variation where the liver includes an accessory hepatic artery. For these instances, the hepatic artery cannula described above can be a double-headed (e.g., Y-shaped) cannula. An exemplary embodiment of a Y-shaped hepatic artery cannula  2642 , is shown in  FIGS. 21E-21G , where like numbers are used to denote corresponding features in the cannula  2600 . The bifurcated design of hepatic artery cannula  2642  can allow the system  100  to treat both vessels as one input for hepatic artery flow without changing the configuration of the system  100  and/or the controller  150 . 
     In an alternative embodiment, when the liver includes an accessory hepatic artery, two hepatic artery cannulas  2600  may be attached to a section of Y-shaped tubing at one end, and the other end may be connected to the organ chamber. 
     Referring to  FIGS. 22A-22D , an exemplary embodiment of a portal vein cannula  2650  is shown. The cannula  2650  is generally tubular in shape and includes a first portion  2654  that is configured to be inserted into tubing used in the system  100  and includes a first orifice  2660 . The first portion  2654  can also include a ring  2652  that can be used to help secure the first portion  2654  inside of the tubing of the system  100  by friction. The cannula  2650  can also include a second portion  2656  that can have a larger diameter than the first portion  2654  and that forms a second orifice  2662 . The second portion  2656  can also include a channel  2658  that is recessed from the surface of the second portion  2656 . In some embodiments, when the user ties the portal vein to the second portion  5626 , the user can place the suture in the channel  2658  to help secure the portal vein. Viewing the cross-section shown in  FIG. 22D , the inside diameter of the cannula  2600  can vary, with a taper  2664  therebetween. The cannula  2650  can be formed in various sizes, lengths, inside diameters, and outside diameters. In some embodiments of the system  600 , it can be advantageous to have a substantially large inside diameter in the first portion  2654  and an even larger inside diameter in the second portion  2656  to offset pressure and flow changes caused by the cannula  2650 . 
     Referring to  FIGS. 22E-22G . in an alternative embodiment the cannula  2650  has a collar  2666  between the first and second portions. The outside diameter of the collar can have a slightly larger diameter than the first portion  2654  to prevent the tubing of the system  100  from extending over the second portion  2656  when inserted. The cannula  2650  may also have a beveled cut end  2668 . 
     The outside diameter of the first portion  2654  can be configured to be press-fit inside of silicone or polyurethane tubing. Thus, while the outside diameter of the first portion  2654  can vary, one exemplary range of possible diameters is 0.410-0.510″. The outside diameter of the second portion  2656  can range between 25-75 Fr, but more specifically between 40-48 Fr. Additionally, the cannula  2650  can be made from various biocompatible materials, such as stainless steel, titanium, and/or plastic (the dimensions of the cannula  2600  can be adapted to be manufacturable using different materials). 
     Referring to  FIGS. 23A-23N , an exemplary hepatic artery connector  3000  is shown. The connector  3000  can be part of the branch  315  leading to the hepatic artery of the liver. For example, the connector  3000  can be inserted into and secured to the wall of the organ chamber  104 . The connector  3000  can include a first portion  3006  that includes a circumferential channel  3007  and defines an opening  3008 . In some embodiments, the outside diameter of the first portion  3006  is sized to couple to ¾″ tubing, although other diameters are possible. In some embodiments, tubing coupled to the first portion  3006  can coupled using friction and/or a common zip tie (or other similar fastener) can be tied around the channel  3007  to secure the tubing connected thereto. The connector  3000  can also include a second portion  3002  that defines an opening  3003 . In some embodiments, the outside diameter of the second portion  3002  can be configured to couple to ¾″ tubing using a press/friction connection, although other sizes are possible. In some embodiments, perfusion fluid flows from the opening  3008  toward the opening  3003 . 
     The connector  3000  can include an interface that is configured to mate with an opening in a wall of the organ chamber  104 . For example, connector  3000  can include a ridge  3003  that is sized to fit within a corresponding opening in a wall of the organ chamber  104 . A backstop  3004  can be larger than the opening to prevent the connector from being inserted too far, and can also provide a surface on which adhesive can be applied to bond the connector  3000  to the organ chamber  104 . In some embodiments, the ridge  3003  can include a protrusion  3011  that is configured to rotationally align the connector  3000  within the organ chamber  104 . For example, in some embodiments, the protrusion  3011  and corresponding opening in the organ chamber  104  can be configured so that the connector  3000  is rotated about a longitudinal axis of the second portion  3003 . In some embodiments, the rotation can be optimized to prevent air bubbles. 
     The connector  3010  can also including a housing  3010  that is configured to house the pressure sensor  130   b . In this embodiment the two pressure sensors make up the pressure sensor  130   b . In such an embodiment, the pressure sensors can be mounted in the openings  3009 , which can provide direct access to the fluid within the connector  3000 . Additionally, some embodiments of the connector  3000  can include an air vent  3005  that can be connected to a valve which can be opened to vent air bubbles trapped within the connector  3000 . In operation, a user can attach one end of a tube to the second portion  3002  and the other end of the tube to the hepatic artery cannula  2600  (which can be connected to the hepatic artery). In some embodiments, the user can place a liver into the organ chamber  104 , connect a cannula  2600  to an end of a piece of tubing, which can be connected to the hepatic artery using a suture. Next, because the size of the liver can vary, the user can then trim the tubing to the proper length and attach it to the second portion  3003 . 
     Referring to  FIGS. 24A-23L , an exemplary portal vein connector  3050  is shown. In some embodiments the portal vein connector  3050  is configured and functions in the same manner as the connector  3000 , except that the first and second portions can be coupled to connect to ⅜″ or ½″ tubing instead of ¾″, although it can be configured to work with other size tubing as well. Also, as should be clear by the name, the portal vein connector can be configured to couple the branch  313  to the portal vein of the liver. 
     While some dimensions are provided above, these dimensions are exemplary only and each of the foregoing components can sized as necessary to achieve the desired flow characteristics. For example, in some embodiments, it can be beneficial to use the largest diameter cannula to avoid introducing undesirable pressure or flow changes. Additionally, in practice, the diameter of the cannula can be chosen by the surgeon such that the largest cannula is used that will physically fit in the vessel. 
     It is noted herein that some consider the “Fr” scale to end at “34.” Thus, to the extent that a Fr size larger than 34 is identified (or an Fr. number that does not exist in the traditional Fr. scale), the size in mm can be calculated by dividing the identified Fr number by 3. 
     15. Flow Clamp 
     Referring to  FIGS. 25A-25B , an exemplary embodiment of the flow clamp  190  is shown. The flow clamp  190  can be used to control the flow and/or pressure of the perfusion fluid to the portal vein of the liver. The flow clamp  190  can include a cover  4001 , a knob  4002 , a pivot  4003 , a pin  4004  a screw  4005 , a bearing  4006 , a slide  4007 , an axle  4008 , and a body  4009 . The slide  4007  can include a groove  4010  and detent  4012  and can be configured to move up and down within the body  4009 . In some embodiments, a tube carrying perfusion fluid is placed within the body  4009  under the slide  4007 .  FIGS. 25C-25D  show the flow clamp  190  with molded components. 
     The flow clamp  190  can be configured to allow a user to quickly engage and disengage the clamp  190 , while still having precise control over the amount of clamping force applied. In this embodiment, the cover  4001 , the knob  4002 , the pivot  4003 , the pin  4004 , the screw  4005 , and the bearing  4006  make up a switch unit  4011 . The pivot  4003  of the switch unit  4011  can rotate about a longitudinal axis formed by the axle  4008  (which can be made up of two separate screws). In this manner, when the switch unit  4011  is engaged (e.g., the screw  4005  is vertical), as shown in  FIG. 25A , the bearing  4006  forces the slide  4007  downward in the body  4009  (which can compress the tube carrying the perfusion fluid, if present, and restricts flow therein). How far down the slide is forced is a function of how extended the screw  4005  is relative to the pivot  4003 . When the switch unit  4011  is disengaged, it is pivoted sideways so that the screw is no longer vertical and does not restrict the movement of the slide  4007 . When the switch unit  4011  is pivoted, the bearing can slide along the grove  4010 . In some embodiments, the switch unit  4011  can “lock” into place when the bearing  4006  comes to rest in the detent  4012 . The user can adjust the amount of flow restriction is imposed by the flow clamp  190  when engaged by rotating the knob  4002 , thereby extending/retracting the screw  4005 . In some embodiments, the pitch of the screw can be 4-40 thread, although other pitches can be used adjust the precision of the flow clamp  190 . 
     16. Priming 
     In some embodiments, the perfusion fluid includes packed red blood cells also known as “bank blood.” Alternatively, the perfusion fluid includes blood removed from the donor through a process of exsanguination during harvesting of the liver. Initially, the blood is loaded into the reservoir  160  and the cannulation locations in the organ chamber assembly are connected with a bypass conduit to enable normal mode flow of perfusion fluid through the system without a liver being present, aka “priming tube.” Prior to cannulating the harvested liver, the system may be primed by circulating the exsanguinated donor blood through the system to heat, oxygenate, and/or filter it. Nutrients, preservatives, and/or other therapeutics may also be provided during priming via the infusion pump of the nutritional subsystem. During priming, various parameters may also be initialized and calibrated via the operator interface during priming. Once primed and running appropriately, the pump flow can be reduced or cycled off, the bypass conduit is removed from the organ chamber assembly, and the liver can be cannulated into the organ chamber assembly. The pump flow can then be restored or increased, as the case may be. The priming process is described more fully below. 
     17. IVC Cannulation 
     In some embodiments, the inferior vena cava (IVC) can be cannulated, though not required. In these embodiments, additional pressure and/or flow sensors can be used to determine the pressure and/or flow of the perfusion fluid flowing from the liver. In some embodiments, the cannulated IVC can be coupled directly to the sensor  140  and/or reservoir. In other embodiments, the IVC can be cannulated for the purpose of directing the drainage of the perfusion fluid (e.g., directed free draining). For example, the uncannulated end of a short tube connected to the IVC can be held in place by a clip so that perfusion fluid drains directly over the measurement drain  2804 . In other embodiments, the IVC is not cannulated, and perfusion fluid can drain freely therefrom. In still other embodiments, the IVC can be partially tied off. 
     In embodiments where the IVC is cannulated and connected to tubing, it can be desirable to keep the length of tubing as short as possible to achieve the desired result. That is, because physiologic IVC pressure is low, even a length of narrow tube can result in an elevated IVC pressure. In embodiments of the system  600  that include pressure exertion on the liver to encourage draining (e.g., pressurizing the chamber  104  as discussed above), the liver may be able to tolerate a longer cannula/tubing. 
     18. Bile Duct Cannulation 
     In some embodiments of the system  600 , the bile duct of the liver can be cannulated using an off the shelf and/or custom cannula. For example, a bile duct cannula of 14 Fr can be used. Additionally, the bile bag  187  can be configured to collect bile produced by the liver. In some embodiments, the bag  187  is clear so the user can visually observe the color of the bile. In some embodiments, the bag  187  can collect up to 0.5 L of bile, although other amounts are possible. In some embodiments, the bag  187  can include graduations that indicate how much bile has been collected. While the system  600  is described as including a soft shell (e.g., the bag  187 ) to collect bile, a hard shell container can also be used. Some embodiments of the system  600  can include a sensor (e.g., capacitive, ultrasonic, and/or cumulative flow rate) to measure the volume of bile collected. This information can then be displayed to the user and/or sent to the Cloud. 
     19. Blood Collection/Filter 
     Some embodiments of the system  600  using whole blood from a donor can include leukocyte filter (not shown). In these embodiments, the leukocyte filter can be used when priming the system to filter blood received from a donor body via a blood collection line connected to a donor&#39;s artery and/or vein. In some embodiments, the leukocyte filter can be configured to filter at least 1500 mL of blood in 6 minutes or less (although other rates are possible). In some embodiments, the leukocyte filter can be configured to remove 30% or more of all leukocytes in up to 1500 mL of whole blood. 
     20. Final Flush Administration Kit 
     At times during operation, it can be desirable to remove all of the perfusion solution from the liver vasculature (e.g., before the liver is implanted into a recipient) without disconnecting the liver from the system  100 . Thus, embodiments of the system  600  can be used with a final flush administration kit. The kit can include a bag (or other container) to collect a volume of liquid (e.g., flush solution and/or perfusate) so that when the flushing solution is administered to the liver (e.g., via ports  4301 ,  4302 ), the system  100  is not overwhelmed by the additional volume of fluid. Thus, in some embodiments, the system  100  can include a drain line (not shown) that can be used to drain fluid from the reservoir  160  and/or elsewhere in the system  100  in such a manner that the liver need not be disconnected from the system  100  before adding additional fluid. In some embodiments, the system can also be setup in a bypass operation where the liver is temporarily isolated from the system  100  using one or more valves. For example, in this embodiment, valves can be used before the ports  4301 ,  4302  to stop fluid flow within the system  100 . Additional drainage ports can then be included between the drains  2804 ,  2806  and the valves. In this embodiment, the flush solution (or any other solution) can be provided via the ports  4301 ,  4302  and drain out of the additional drainage ports without being circulated in the rest of the system  100 . In some embodiments, the drain line can hold at least 3 L of liquid, although this is not required. 
     D. Interface Between Single/Multi Use Modules 
     As shown in  FIG. 3G  and described in further detail below, the multiple use module  650  can include a front-end interface circuit board  636  for interfacing with a front-end circuit board (shown in  FIG. 13J  at  637 ) of the disposable module  634 . As described more fully below, power and drive signal connections between the multiple use module  650  and the disposable module  634  can be made by way of corresponding electromechanical connectors  640  and  647  on the front-end interface circuit board  636  and the front-end circuit board  637 , respectively. By way of example, the front-end circuit board  637  can receive power for the disposable module  634  from the front-end interface circuit board  636  via the electromechanical connectors  640  and  647 . The front-end circuit board  637  can also receive drive signals for various components (e.g., the heater assembly  110 , the flow clamp  190 , and the oxygenator  114 ) from the controller  150  via the front-end interface circuit board  636  and the electromechanical connectors  640  and  647 . The front-end circuit board  637  and the front-end interface circuit board  636  can exchange control and data signals (e.g., between the controller  150  and the single use module  634 ) by way of optical connectors (shown in  FIG. 20B  at  648 ). As described in more detail below, the connector configuration employed between the front-end  637  and front-end interface  636  circuit boards can ensure that critical power and data interconnections between the single and multiple use modules  634  and  650 , respectively, continue to operate even during transport over rough terrain, such as may be experienced during organ transport. 
     Turning now to the installation of the single use module  634  into the multiple use module  650 ,  FIG. 3H  shows a detailed view of the above-mentioned bracket assembly  638  located on the multiple use module  650  for receiving and locking into place the single use module  634 .  FIG. 3F  shows a side perspective view of the single use module  634  being installed onto the bracket assembly  638  and into the multiple use module  650 , and  FIG. 3C  shows a side view of the single use module  634  installed within the multiple use module  650 . The bracket assembly  638  includes two mounting brackets  642   a  and  642   b , which can mount to an internal side of a back panel of the housing  602  via mounting holes  644   a - 644   d  and  646   a - 646   d , respectively. A cross bar  641  extends between and rotatably attaches to the mounting brackets  642   a  and  642   b . Locking arms  643  and  645  are spaced apart along and radially extend from the cross bar  641 . Each locking arm  643  and  645  includes a respective downward extending locking projection  643   a  and  645   b . A lever  639  attaches to and extends radially upward from the cross bar  641 . Actuating the lever  639  in the direction of the arrow  651  rotates the locking arms  643  and  645  toward the back  606   b  of the housing  602 . Actuating the lever  639  in the direction of the arrow  653  rotates the locking arms  643  and  645  toward the front of the housing  602 . 
     As described above with respect to  FIG. 6E , the perfusion pump interface assembly  300  includes four projecting heat staking points  321   a - 321   d . During assembly, the projections  321   a - 321   d  are aligned with corresponding apertures (e.g.,  657   a ,  657   b  in  FIG. 13B ) and heat staked through the apertures to rigidly mount the outer side  304  of the pump interface assembly  300  onto the C-shaped bracket  656  of the single use module chassis  635 . 
     During installation, in a first step, the single use module  634  is lowered into the multiple use module  650  while tilting the single use module  634  forward (shown in  FIG. 3F ). This process slides the projection  662  into the slot  660 . As shown in  FIG. 6E , it also positions the flange  328  of the pump interface assembly  300  within the docking port  342  of the perfusion pump assembly  106 , and the tapered projections  323   a  and  323   b  of the pump interface assembly  300  on the clockwise side of corresponding ones of the features  344   a  and  344   b  of the pump assembly bracket  346 . In a second step, the single use module  634  is rotated backwards until locking arm cradles of the single use module chassis  635  engage projections  643  and  645  of spring-loaded locking arm  638 , forcing the projections  643  and  645  to rotate upward, until locking projections  643   a  and  645   a  clear the height of the locking arm cradles, at which point the springs cause the locking arm  638  to rotate downward, allowing locking projections  643   a  and  645   a  to releasably lock with locking arm cradles of the disposable module chassis  635 . This motion causes the curved surface of  668  of the single use module projection  662  of  FIG. 13B  to rotate and engage with a flat side  670  of the basin slot  660  of  FIG. 20B . Lever  639  can be used to rotate the locking arm  638  upwards to release the single use module  635 . 
     As shown in  FIG. 6E , this motion also causes the pump interface assembly  300  to rotate in a counterclockwise direction relative to the pump assembly  106  to slide the flange  328  into the slot  332  of the docking port  342 , and at the same time, to slide the tapered projections  323   a  and  323   b  under the respective bracket features  344   a  and  344   b . As the tapered projections  323   a  and  323   b  slide under the respective bracket features  344   a  and  344   b , the inner surfaces of the bracket features  344   a  and  344   b  engage with the tapered outer surfaces of the tapered projections  323   a  and  323   b  to draw the inner side  306  of the pump interface assembly  300  toward the pump driver  334  to form the fluid tight seal between the pump interface assembly  300  and the pump assembly  106 . The lever  639  may lock in place to hold the disposable module  634  securely within the multiple use module  650 . 
     Interlocking the single use module  374  into the multiple use module  650  can form both electrical and optical interconnections between the front-end interface circuit board  636  on the multiple use module  650  and the front-end circuit board  637  on the single use module  634 . The electrical and optical connections enable the multiple use module  650  to power, control and collect information from the single module  634 .  FIG. 20A  is an exemplary conceptual drawing showing various optical couplers and electromechanical connectors on the front-end circuit board  637  of the single-use disposable module  634  used to communicate with corresponding optical couplers and electromechanical connectors on the front-end interface circuit board  636  of the multiple use module  650 . Since this correspondence is one for one, the various optical couplers and electromechanical connectors are described only with reference to the front-end circuit board  637 , rather than also depicting the front-end circuit board  650 . 
     According to the exemplary embodiment, the front-end circuit board  637  receives signals from the front-end interface circuit board  636  via both optical couplers and electromechanical connectors. For example, the front-end circuit board  637  receives power  358  from the front-end interface circuit board  636  via the electromechanical connectors  712  and  714 . The front-end circuit board  637  applies the power to the components of the single use module  634 , such as the various sensors and transducers of the single use module  634 . Optionally, the front-end circuit board  637  converts the power to suitable levels prior to distribution. The front-end interface circuit board  636  can also provide the heater drive signals  281   a  and  281   b  to the applicable connections  282   a  on the heater  246  of  FIG. 6E  via the electromechanical connectors  704  and  706 . Similarly, the electromechanical connectors  708  and  710  can couple the heater drive signals  283   a  and  283   b  to the applicable connections in  282   b  of the heater  248 . 
     According to the exemplary embodiment, the front-end circuit board  637  can receive signals from temperature, pressure, fluid flowrate, and oxygenation/hematocrit sensors, amplify the signals, convert the signals to a digital format, and provide them to the front-end interface circuit board  636  by way of electrical and/or optical couplers. For example, the front-end circuit board  637  can provide the temperature signal  121  from the sensor  120  on the heater plate  250  to the front-end interface circuit board  636  by way of the optical coupler  676 . Similarly, the front-end circuit board  637  can provide the temperature signal  123  from the sensor  122  on the heater plate  252  to the front-end interface circuit board  636  by way of the optical coupler  678 . The front-end-circuit board  637  can also provide the perfusion fluid temperature signals  125  and  127  from the thermistor sensor  124  to the front-end interface circuit board  636  via respective optical couplers  680  and  682 . Perfusion fluid pressure signals  129 ,  131  and  133  can be provided from respective pressure transducers  126 ,  128  and  130  to the front-end interface circuit board  636  via respective optical couplers  688 ,  690  and  692 . The front-end circuit board  637  can also provide perfusion fluid flow rate signals  135 ,  137  and  139  from respective flow rate sensors  134 ,  136  and  138  to the front-end interface circuit board  636  by way of respective optical couplers  694 ,  696  and  698 . Additionally, the front-end circuit board  637  can provide the oxygen saturation  141  and hematocrit  145  signals from the sensor  140  to the front-end interface circuit board  636  by way of respective optical couplers  700  and  702 . In another implementation, the front-end circuit receives signals from integrated blood gas analysis probes. In another implementation the front-end board passes control signals to a fluid path restrictor to facilitate real time control of the division of perfusate flow between the portal vein and hepatic artery conduits. The controller  150  can employ the signals provided to the front-end interface circuit board  636 , along with other signals, to transmit data and otherwise control operation of the system  600 . 
     While the front-end circuit board  637  is described with the foregoing couplers, more or fewer couplers can be used based on the number of connections necessary. 
     In some exemplary embodiments, one or more of the foregoing sensors can be wired directly to the main system board  718  for processing and analysis, thus by-passing the front-end interface board  636  and front-end board  637  altogether. Such embodiments can be desirable where the user prefers to re-use one or more of the sensors prior to disposal. In one such example, the flow rate sensors  134 ,  136  and  138  and the oxygen and hematocrit sensor  140  are electrically coupled directly to the system main board  718  through electrical coupler  611  shown in  FIG. 23C , thus by-passing any connection with the circuit boards  636  and  637 . 
       FIG. 20B  illustrates the operation of an exemplary electromechanical connector pair of the type employed for the electrical interconnections between the circuit boards  636  and  637 . Similarly,  FIG. 20C  illustrates the operation of an optical coupler pair of the type employed for the optically coupled interconnections between the circuit boards  636  and  637 . One advantage of both the electrical connectors and optical couplers employed is that they ensure connection integrity, even when the system  600  is being transported over rough terrain, for example, such as being wheeled along a tarmac at an airport, being transported in an aircraft during bad weather conditions, or being transported in an ambulance over rough roadways. The power for the front-end board  637  is isolated in a DC power supply located on the front-end interface board  636 . 
     As shown in  FIG. 20B , the electromechanical connectors, such as the connector  704 , include a portion, such as the portion  703 , located on the front-end interface circuit board  636  and a portion, such as the portion  705 , located on the front-end circuit board  637 . The portion  703  includes an enlarged head  703   a  mounted on a substantially straight and rigid stem  703   b . The head  703  includes an outwardly facing substantially flat surface  708 . The portion  705  includes a substantially straight and rigid pin  705  including an end  705   a  for contacting the surface  708  and a spring-loaded end  705   b . Pin  705  can move axially in and out as shown by the directional arrow  721  while still maintaining electrical contact with the surface  708  of the enlarged head  703   a . This feature enables the single use module  634  to maintain electrical contact with the multiple use module  650  even when experiencing mechanical disturbances associated with transport over rough terrain. An advantage of the flat surface  708  is that it allows for easy cleaning of the interior surface of the multiple use module  650 . According to the illustrative embodiment, the system  600  employs a connector for the electrical interconnection between the single use disposable  634  and multiple use 650 modules. An exemplary connector is part no. 101342 made by Interconnect Devices. However, any suitable connector may be used. 
     Optical couplers, such as the optical couplers  684  and  687  of the front-end circuit board  637 , are used and include corresponding counterparts, such as the optical couplers  683  and  685  of the front-end interface circuit board  636 . The optical transmitters and optical receiver portions of the optical couplers may be located on either circuit board  636  or  637 . 
     As in the case of the electromechanical connectors employed, allowable tolerance in the optical alignment between the optical transmitters and corresponding optical receivers enables the circuit boards  636  and  637  to remain in optical communication even during transport over rough terrain. According to the illustrative embodiment, the system  100  uses optical couplers made under part nos. 5FH485P and/or 5FH203 PFA by Osram. However, any suitable coupler may be used. 
     The couplers and connectors can facilitate the transmission of data within the system  600 . The front-end interface circuit board  636  and the front-end board  637  transmit data pertaining to the system  600  in a paced fashion. As shown in  FIG. 20C , circuit board  636  transmits to the front-end board  637  a clock signal that is synchronized to the clock on the controller  150 . The front-end circuit board  637  receives this clock signal and uses it to synchronize its transmission of system data (such as temperatures, pressures, or other desired information) with the clock cycle of the controller  150 . This data is digitized by a processor on the front-end circuit board  637  according to the clock signal and a pre-set sequence of data type and source address (e.g., type and location of the sensor providing the data). The front-end interface circuit board  636  receives the data from the front-end board  637  and transmits the data set to the main board  618  for use by the controller  150  in evaluation, display, and system control. Additional optical couplers can be added between the multiple use module and single use module for transmission of control data from the multiple use module to the single use module, such data including heater control signals or clamp/flow restrictor controls. 
     IV. Description of Exemplary System Operation 
     A. Generally 
     As described below, the system  600  can be configured to operate in multiple modes such as: perfusion circuit priming mode, organ stabilization mode, maintenance mode, chilling mode, and self-test/diagnostic mode. During each mode the system (vis-à-vis the controller  150 ) can be configured to operate in different manners. For example, as described more fully below, during the different modes of operation characteristics of, for example, perfusion fluid flow rates, perfusion fluid pressure, perfusion fluid temperature, etc. can vary. 
     Additionally, some embodiments of the system  600  can include a self-test mode in which diagnostics can be performed. For example, the system  600  can automatically test circuits and sensors in the single use and multiple use modules before the organ is instrumented on the system. The system  600  can also check to ensure that the single use module is installed properly in the multiple use module (e.g., all connections are secure and functioning). In the event of a failure, the system can inform the user and inhibit further operation of the system until the issue is resolved. 
     B. Temperature Monitoring and Control 
     In general, the temperature of an organ contained in the system  600  can be controlled by circulating warmed or cooled perfusion fluid therethrough. Thus, the perfusion fluid itself can be used to control the temperature of the organ without using a dedicated heater/cooler within the organ chamber  104 . 
     In some embodiments of the system  600 , the controller  150  can be configured to receive signals from one or more temperature sensors such as temperature sensors  120 ,  122 ,  124 . While these sensors are described as being located at or near the heater  110 , this is not required. For example, temperature sensors that measure the temperature of the perfusion fluid can be placed throughout the system  100  such as in the branches  313 ,  315 , in the measurement drain  2804 , in the drain  2806 , and/or in the reservoir  160 . Additional temperature sensors can also be included to measure other temperature aspects of the system  600 . For example, the system  600  can include ambient air temperature sensors that measure the temperature of the environment around the system  600 , temperature sensors that measure the temperature of the environment within the organ chamber  104 , and/or sensors that measure the temperature of a surface and/or internal portion of the organ contained therein. 
     The controller  150  can use information from the various temperature sensors in the system  600  in order to control the temperature of the environment and/or perfusion fluid therein. For example, in some embodiments the controller  150  can maintain the perfusion fluid exiting the heater at a desired temperature. In some embodiments, the controller  150  can determine a temperature differential between the perfusion fluid flowing into and out of the organ. If the temperature differential is large, the controller  150  can indirectly determine the temperature of the organ and adjust the temperature of the perfusion fluid flowing into the organ to achieve the desired organ temperature. Additionally, in some embodiments the organ chamber  104  can include a heater/cooler that heats/cools the environment within the organ chamber  104 , such as a resistive heater or a thermoelectric cooler. Such a heater/cooler can be controlled by the controller  150 . 
     While much of the disclosure herein focuses on heating an organ to a desired temperature, this is not intended to be limiting. In some embodiments, the system  600  can include a cooling unit (not shown) in addition to and/or instead of the heater  110 . In such embodiments, the cooling unit can be used to cool the perfusion fluid and ultimately cool the organ itself. This can be useful during, for example, post-preservation chilling procedures used with a heart, lung, kidney, and/or liver. In some embodiments, the cooling unit can be comprised of a gas exchanger with an integrated water-cooled feature, although other configurations are possible. 
     C. Blood Flow Monitoring and Control 
     Many organs in the human body receive a blood supply with a single set of pressure and flow characteristics (e.g., kidney, lung). To the extent that these organs are maintained ex vivo in an organ care system, a single pump and a single supply line can be used to provide perfusion fluid thereto. The liver, however, is different from other organs in that it has two blood supplies, each with different pressure and flow characteristics. As noted above, the liver receives approximately ⅓ of its blood supply from the hepatic artery and approximately ⅔ of its blood supply from the portal vein. The hepatic artery provides a pulsatile blood flow at a relatively high pressure, but low flow rate. In contrast, the portal vein provides a substantially nonpulsatile blood flow at a relatively low pressure, but high flow rate. Because of these different flow characteristics, providing perfusion fluid to an ex vivo liver can present challenges when a single pump is used. Thus, some embodiments of the organ care system  600  include a system that is configured to provide a dual flow of perfusion fluid in a manner that mimics the human body. Specifically, the branch  315  of the system  100  can provide perfusion fluid to the hepatic artery in a pulsatile, high-pressure, low flow manner. The branch  313  of the system  100  can provide perfusion fluid to the portal vein in a non-pulsatile, low pressure, high flow manner. 
     As noted above, the pump  106  can provide a flow of perfusion fluid at a predetermined flow rate, which can be split at the divider  105 . In some embodiments, the fluid flow can be split between the hepatic artery and the portal vein at a ratio of between 1:2 and 1:3. In some embodiments, the divider is configured such that the branch  313  uses ⅜″ tubing and the branch  315  uses ¾″ tubing. In some embodiments, a portal vein clamp can be used to help attain this split ratio and/or can be used to restrict the resulting flow in the portal vein leg of the circuit (e.g., branch  313 ) so as to create higher pressure flow in the hepatic artery leg of the circuit (e.g., branch  315 ) and lower pressure flow in the parallel portal vein leg of the circuit. In some embodiments, a user can manually adjust the portal vein clamp (e.g., such as the flow clamp  190 ) to effect a hepatic pressure in the acceptable range and adjust the pump flow rate to provide an acceptable hepatic artery flow rate. The combination of these two adjustments (portal vein clamp and pump flow rate) can result in acceptable hepatic artery flow and pressure and correspondingly acceptable portal vein pressure and flow rate. 
     In some embodiments, the portal vein clamp can be implemented as mechanism controlled by the system, such as an electromechanical or pneumatically controlled clamp. The system can adjust the pump flow and portal vein clamp in response to pressure and flow values measured on the hepatic artery and portal vein branches to effect pressures and flows in acceptable ranges for these paths. For example, in embodiments that use an automated portal vein clamp, if the controller  150  detects that the flow in the hepatic artery branch  315  is too low, the controller  150  can increase the flow rate provided by the pump  106 . Likewise, if the controller detects that the pressure in the hepatic artery branch  315  is too low, the controller  150  can cause the portal vein clamp to close slightly in order to increase the pressure in hepatic artery branch  315 . 
     In some embodiments, the controller  150  can monitor the level of perfusion fluid in the system  600 . In the event that the amount of perfusion fluid is below recommended levels, the controller  150  can alert the user to this fact so that they may take recommended action such as adjusting pump flow and/or adding additional perfusion fluid to the system. Additionally, if the level is below a critical level, the controller  150  can automatically reduce the pump flow to a reduced or minimal level while alerting the user. 
     D. Gas Monitoring and Control 
     In some embodiments, the system  600  can be configured to automatically control pressure within the system by varying the flow rate of the pump  106  and/or by controlling the infusion of a vasodilator. For example, one of the infusions provided by the solution pump  631  can be or can contain a vasodilator. When a vasodilator is administered, the perfusion fluid pressure for a given flow rate within the system  100  can drop (due to the dilation of the vasculature in the liver). Thus, for example, reducing the infusion rate of a vasodilator can result in increased perfusate pressure. An optimal balance can be achieved at the least amount of vasodilator that results in adequate liver perfusion. 
     The system  600  can be configured to control the gas content in the perfusion fluid in such a manner that it mimics the human body. Accordingly, in some embodiments, the system  600  includes a gas exchanger (e.g., gas exchanger  114 ) that is configured to provide O 2  and/or other desirable gases to the perfusion fluid. In principle, a gas exchanger works by facilitating the flow of a high concentration of gas to an area of low concentration of gas. In this way, the O 2  in the maintenance gas (e.g., the gas provided to the gas exchanger) can be diffused to the O 2  depleted perfusion fluid and the relatively high level of CO 2  in the perfusion fluid can be diffused to the maintenance gas before it is exhausted from the gas exchanger. The maintenance gas provided to the gas exchanger can be comprised of the appropriate mixture of O 2 , N 2 , and CO 2 , where the concentration of O 2  is higher, and the concentration of CO 2  is lower than that in the perfusion solution exiting a metabolically active liver. In some instances, the gas is comprised of only O 2  and N 2 . 
     Some embodiments of the system  600  include an oxygenation sensor (e.g., sensor  140 ) that can be used to provide information about the oxygenation of the perfusion fluid. If the oxygenation level is too low, the rate of gas supplied to the gas exchanger can be increased to raise the level of oxygen in the perfusion fluid. Likewise, if the level is too high, the rate of gas supplied to the gas exchanger can be decreased. Control of the gas supply to the gas exchanger can be performed manually by the user (e.g., through the operator interface module  146 ) and/or automatically. In an automated embodiment, the controller  150  can automatically increase or decrease the gas flow from the onboard gas supply to the gas exchanger to effect the desired change in oxygenation level. 
     The liver, however, can present an additional challenge providing the proper perfusion fluid gas content. Because of its inherent metabolism, the liver produces CO 2  that replaces O 2  contained in the perfusate. In some embodiments, measuring the O 2  levels alone is not sufficient to determine the amount of CO 2  present in the perfusion fluid. Thus, some embodiments the system  600  can be configured to separately monitor the level of CO 2  in the perfusion fluid to ensure that it stays within an acceptable range. In these embodiments, the gas exchanger can also be used to reduce or even eliminate CO 2  from the perfusion fluid as it passes therethrough. 
     In order to determine the carbon dioxide level in the perfusate, some embodiments of the system  600  incorporate blood sample ports so that the user can withdraw blood samples to assess the levels of carbon dioxide in the perfusate via a third-party blood gas analyzer. Based on this analysis, the user can assign a gas flow rate into the gas exchanger in order to affect an acceptable carbon dioxide level in the perfusate. For example, higher than acceptable levels of carbon dioxide can require a higher gas flow rate to the gas exchanger to reduce the resulting level of carbon dioxide. However, it can be advantageous to keep the gas flow to the gas exchanger as low as possible in order to maximize the life of the onboard gas supply—an important factor in extended transport scenarios. 
     Some embodiments of the system  600  can incorporate a blood gas analysis system (not shown). In these embodiments, the blood gas analysis system can be configured to sample perfusion fluid flowing within the system  100 . For example, the blood gas analysis system can be configured to take samples of perfusion fluid at one or more locations in the system  100  such as in branches  313 ,  315 , in the measurement drain  2804 , and/or in the main drain  2806 . By measuring the concentration of oxygen and/or carbon dioxide in the perfusate, the controller  150  can automatically increase or decrease, as the case may be, the flow of gas to the gas exchanger to obtain the desired gas levels in the perfusion fluid. 
     E. Solution Delivery and Control 
     As noted above, some embodiments of the system  600  can include a solution pump that is configured to provide one or more solutions. In some specific embodiments, the runtime perfusion solution comprises three solutions. The first solution can comprise one or more energy-rich component (e.g., one or more carbohydrates); and/or one or more amino acids; and/or one or more electrolytes; and/or one or more buffering agents (e.g., bicarbonate). In some particular embodiments, the first solution can comprise TPN (Clinimix E), buffering agents (e.g., sodium bicarbonate and phosphates), heparin and insulin. The second solution can comprise one or more vasodilators. In some particular embodiments, the vasodilator used is Flolan®. The third solution can comprise bile acid or salts (e.g., Na Taurocholic acid salt). In some embodiments, the three solutions are kept separate from one another and administered separately (e.g., using the three channels of the solution pump  631 ). In other embodiments, the three solutions, optionally all aqueous solutions, can be mixed together to form the runtime perfusion solutions. In certain embodiments, a sufficient amount of heparin can be provided (e.g., amount sufficient to maintain activated clotting time (ACT) for about or more than 400 seconds ACT). 
     V. Solutions 
     Exemplary solutions that can be used in the organ care system  600  according to one or more embodiments are now described. Various solutions can be used at different times in the preservation/treatment process. 
     A. Donor Flush 
     If the organ being harvested is an abdominal organ, the surgeon performing the harvest can perform a donor flush in vivo or ex vivo to remove donor blood and/or other matter from the organ. The flush used during the donor flush can be an intracellular or extracellular solution such as the University of Wisconsin Solution, a modified University of Wisconsin Solution, or a histidine-tryptophan-ketoglutarate (HTK) solution. 
     B. Initial Flush Solution 
     In some embodiments, after the donor flush (regardless of whether the donor flush was done in vivo or ex vivo) and before it is placed in the preservation chamber of the organ care system  600 , an initial flush solution can be used to flush the liver in vivo or ex vivo in order to remove the residual blood and any solution used in the donor flush. This flush solution is referred to herein as the initial flush solution, which is optionally a sterile solution. In some embodiments, the main components of the initial flush solution can include a buffered isotonic electrolyte solution, such as Plasmalyte, and anti-inflammatory, such as SoluMedrol. In some embodiments, the initial flush can be used to remove the fluid used during the donor flush. In some embodiments, the main components of the initial flush solution can include electrolytes and buffering agents. Non-limiting examples of the electrolytes include various salts of sodium, potassium, calcium, magnesium, chloride, hydrogen phosphate, and hydrogen carbonate. A proper combination of the electrolytes in suitable concentrations can help maintain the physiological osmotic pressure of the intracellular and extracellar environment in liver. Non-limiting examples of the buffering agents include bicarbonate ions. The buffering agents in the initial flush solution can serve to maintain the pH value inside the liver organ to be at or close to the physiological state, e.g., about 7.3 to 7.6, 7.4 to 7.6, or 7.4 to 7.5. Preferably, after the liver is subjected to the initial flush and cooled according to one more embodiments described herein, the harvested liver can be placed into the organ care system  600  according to one more embodiments. 
     C. Priming Solution and Additives 
     In certain embodiments, prior to the placement of the liver into the organ care system  600 , the organ care system  600  can be primed with a priming solution. The priming solution can be sterile and can be used to evaluate the physical integrity of the system and/or to help remove the air in the system. The composition of the priming solution can be similar or identical to that of the runtime perfusion solution, described in more detail below. The priming solution can include certain additives to render the system compatible with liver preservation. For instance, the liver regularly produces coagulation factors promoting blood coagulation. In order to prevent the blood (e.g., donor&#39;s blood used as part of the perfusion fluid for preserving the liver on the organ care system  600 ) from clotting during preservation, anti-clotting agents can be added to the priming solution as additives. Non-limiting examples of anti-clotting agents include heparin. Heparin can be administered throughout the preservation session to maintain ACT (activated clotting time) of ≥400 seconds, although other ACT values can be used. Depending on the liver being maintained, the amount of heparin needed to achieve the desired ACT can vary. In some embodiments, the heparin can be provided continuously or at intervals such as at 0-, 3-, and 6-hours post-instrumentation on the system  600 . In certain embodiments, the organ care system  600  can be primed by a blood product (e.g., donor&#39;s blood) or synthetic blood product prior to the placement of the liver into the organ care system  600 . In certain embodiments, the system  600  can be primed by the priming solution and/or the blood or synthetic blood product. The system  600  can be primed by the mixture of the priming solution and the blood or synthetic blood product, or by the priming solution and the blood or synthetic blood product sequentially. In some embodiments, the organ care system  600  is primed with the perfusion fluid described herein (e.g., the perfusion fluid used to preserve the organ). Alternatively, or additionally, any one of the following combined with either albumen or dextran can also be used: donor blood, red blood cells (RBC), or RBCs plus fresh frozen plasma plus 
     Table 1 sets forth components that can be used in an exemplary priming solution. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Composition of Exemplary Priming Solution 
               
            
           
           
               
               
               
               
            
               
                   
                 Component 
                 Amount 
                 Specification 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 pRBCs 
                 1200-1500 
                 ml 
                 ±about 10% 
               
               
                   
                 25% Albumin 
                 400 
                 ml 
                 ±about 10% 
               
               
                   
                 PlasmaLyte 
                 700 
                 ml 
                 ±about 10% 
               
               
                   
                 Cefazoline or 
                 1 
                 g 
                 ±about 10% 
               
               
                   
                 equivalent antibiotic 
               
               
                   
                 (gram positive and 
               
               
                   
                 gram negative) 
               
               
                   
                 Cipro or equivalent 
                 100 
                 mg 
                 ±about 10%. 
               
               
                   
                 antibiotic (gram 
               
               
                   
                 positive and gram 
               
               
                   
                 negative) 
               
               
                   
                 Solu-Medrol or 
                 500 
                 mg 
                 ±about 10%. 
               
               
                   
                 equivalent anti- 
               
               
                   
                 inflammatory 
               
               
                   
                 HCO 3   −   
                 50 
                 mmol 
                 ±about 10%. 
               
               
                   
                 Multivitamin 
                 1 
                 unit 
               
               
                   
                 Calcium Gluconate 
                 4.65 
                 mEq 
                 ±about 10%. 
               
               
                   
                 Heparin (optional) 
                 10000 
                 Units 
                 ±about 10%. 
               
               
                   
                   
               
            
           
         
       
     
     The exemplary priming solution can be added to the organ care system  600  through the priming step  5024 , as more fully described with reference to  FIG. 29  (described more fully below). 
     D. Runtime Perfusion Solution 
     During the preservation of the harvested liver in the organ care system  600  (e.g., during transport), a perfusion fluid or perfusate, can be used to perfuse the liver and maintain the liver function at or near physiological conditions. In certain embodiments, the perfusion fluid comprises a runtime perfusion solution (also referred to as a maintenance solution) and/or a blood product, e.g., donor&#39;s blood, other individual&#39;s compatible blood, or synthetic blood. The perfusion fluid can be periodically/continuously infused by, for example, the solution pump  631  in order to provide nutrients that can maintain the liver during preservation. In some embodiments, the runtime perfusion solution and/or the blood product are sterile. 
     The compositions of the runtime perfusion solution and the priming solution are now described in more detail. According to certain embodiments, the runtime perfusion solution with particular solutes and concentration is selected and proportioned to enable the organ to function at physiologic or near physiologic conditions. For example, such conditions include maintaining organ function at or near a physiological temperature and/or preserving the liver in a state that permits normal cellular metabolism, such as protein synthesis, glucose storage, lipid metabolism, and bile production. In some embodiments, the priming solution and runtime solution can be selected to be similar or even identical to one another. 
     In certain embodiments, the runtime perfusion solution is formed from compositions by combining components with a fluid, from more concentrated solutions by dilution, or from more dilute solutions by concentration. In exemplary embodiments, suitable runtime perfusion solutions include an energy source, and/or one or more stimulants to assist the organ in continuing its normal physiologic function prior to and during transplantation, and/or one or more amino acids selected and proportioned so that the organ continues its cellular metabolism during perfusion. The runtime perfusion solution can include any therapeutic agents described in more detail below. Cellular metabolism includes, for example conducting protein synthesis while functioning during perfusion. Some illustrative solutions are aqueous based, while other illustrative solutions are non-aqueous, for example organic solvent-based, ionic-liquid-based, or fatty-acid-based. 
     The runtime perfusion solution can include one or more energy-rich components to assist the liver in conducting its normal physiologic function. These components can include energy rich materials that are metabolizable, and/or components of such materials that an organ, e.g., liver, can use to synthesize energy sources during perfusion. Exemplary sources of energy-rich molecules include, for example, one or more carbohydrates. Examples of carbohydrates include monosaccharides, disaccharides, oligosaccharides, polysaccharides, or combinations thereof, or precursors or metabolites thereof. While not meant to be limiting, examples of monosaccharides suitable for the solutions include octoses; heptoses; hexoses, such as fructose, allose, altrose, glucose, mannose, gulose, idose, galactose, and talose; pentoses such as ribose, arabinose, xylose, and lyxose; tetroses such as erythrose and threose; and trioses such as glyceraldehyde. While not meant to be limiting, examples of disaccharides suitable for the solutions include (+)-maltose (4-O-(α-D-glucopyranosyl)-α-D-glucopyranose), (+)-cellobiose (4-O-(β-D-glucopyranosyl)-D-glucopyranose), (+)-lactose (4-O-(β-D-galactopyranosyl)-β-D-glucopyranose), sucrose (2-O-(α-D-glucopyranosyl)-β-D-fructofuranoside). While not meant to be limiting, examples of polysaccharides suitable for the solutions include cellulose, starch, amylose, amylopectin, sulfomucopolysaccharides (such as dermatane sulfate, chondroitin sulfate, sulodexide, mesoglycans, heparan sulfates, idosanes, heparins and heparinoids), dextrin, and glycogen. In some embodiments, monossacharides, disaccharides, and polysaccharides of both aldoses, ketoses, or a combination thereof are used. One or more isomers, including enantiomers, diastereomers, and/or tautomers of monosacharides, disaccharides, and/or polysaccharides, including those described and not described herein, can be employed in the runtime perfusion solution described herein. In some embodiments, one or more monossacharides, disaccharides, and/or polysaccharides can have been chemically modified, for example, by derivatization and/or protection (with protecting groups) of one or more functional groups. In certain embodiments, carbohydrates, such as dextrose or other forms of glucose are preferred. 
     Other possible energy sources include, co-enzyme A, pyruvate, flavin adenine dinucleotide (FAD), thiamine pyrophosphate chloride (co-carboxylase), β-nicotinamide adenine dinucleotide (NAD), β-nicotinamide adenine dinucleotide phosphate (NADPH), and phosphate derivatives of nucleosides, e.g., nucleotides, including mono-, di-, and tri-phosphates (e.g., UTP, GTP, GDF, and UDP), coenzymes, or other bio-molecules having similar cellular metabolic functions, and/or metabolites or precursors thereof. For example, phosphate derivatives of adenosine, guanosine, thymidine ( 5 -Me-uridine), cytidine, and uridine, as well as other naturally and chemically modified nucleosides are contemplated. 
     In certain embodiments, one or more carbohydrates can be provided along with a phosphate source, such as a nucleotide. The carbohydrate can help enable the organ to produce ATP or other energy sources during perfusion. The phosphate source can be provided directly through ATP, ADP, AMP or other sources. In other illustrative embodiments, a phosphate is provided through a phosphate salt, such as glycerophosphate, sodium phosphate or other phosphate ions. A phosphate can include any form thereof in any ionic state, including protonated forms and forms with one or more counter ions. The energy source used can depend on the type of organ being perfused (e.g., adenosine can be omitted when perfusing a liver). 
     One of the liver&#39;s important functions is to produce bile liquid. In some embodiments, the runtime perfusion solution comprises one or more compounds supporting the production of bile by the liver. Non-limiting examples of such compounds include cholesterol, primary bile acids, secondary bile acids, glycine, taurine, and bile acids (bile salts) to promote production of bile by the liver ex vivo, all of which can be used by the liver to produce bile. In some specific embodiments, the bile salt is Na Taurocholic acid salt. 
     Because of the liver&#39;s function as the metabolism powerhouse of the body, it is typically in constant need of energy source and oxygen. Thus, in addition to maintaining the proper concentration of the energy source compounds in the perfusion liquid, the organ care system  600  described herein can also configured to provide constant oxygen supply to the preserved liver. In some embodiments, the oxygen is provided by diffusing an oxygen gas flow through the perfusion liquid (e.g., in the gas exchanger  114 ) or the blood product to dissolve or saturate oxygen in the liquid medium, e.g., by binding oxygen to the hemoglobin in the blood product. In certain embodiments, the perfusion liquid supplied to the liver contains O 2  in PaO 2 ≥200 mmHg (arterial perfusate). In certain embodiments, the perfusion liquid supplied to the liver contains less than PaCO 2 ≤40 mmHg of carbon dioxide thereby promoting and maintaining the oxidative metabolic functions of the liver. In certain embodiments, the perfusion liquid contains less than 30 mmHg≤PACO2 of carbon dioxide thereby maintaining the pH value in the liver to maintain its biological functions. 
     The runtime perfusion solution described herein can include one or more amino acids, preferably a plurality of amino acids, to support protein synthesis by the organ&#39;s cells. Suitable amino acids include, for example, any of the naturally-occurring amino acids. The amino acids can be, in various enantiomeric or diastereomeric forms. For example, solutions can employ either D- or L-amino acids, or a combination thereof, e.g., solutions enantioenriched in more of the D- or L-isomer or racemic solutions. Suitable amino acids can also be non-naturally occurring or modified amino acids, such as citrulline, ornithine, homocystein, homoserine, β-amino acids such as β-alanine, amino-caproic acid, or combinations thereof. 
     Certain exemplary runtime perfusion solutions include some but not all naturally occurring amino acids. In some embodiments, runtime perfusion solutions include essential amino acids. For example, a runtime perfusion solution can be prepared with one or more or all of the following amino acids: Glycine, Alanine, Arginine, Aspartic Acid, Glutamic Acid, Histidine, Isoleucine, Leucine, Methionine, Phenylalanine, Proline, Serine, Thereonine, Tryptophan, Tyrosine, Valine, and Lysine acetate. 
     In certain embodiments, non-essential and/or semi-essential amino acids are not included in the runtime perfusion solution. For example, in some embodiments, asparagine, glutamine, and/or cysteine are not included. In other embodiments, the solution contains one or more non-essential and/or semi-essential amino acids. Accordingly, in some embodiments, asparagine, glutamine, and/or cysteine are included. 
     The runtime perfusion solution can also contain electrolytes, particularly calcium ions for facilitating enzymatic reactions, and/or maintain osmotic pressure within the liver. Other electrolytes can be used, such as sodium, potassium, chloride, sulfate, magnesium and other inorganic and organic charged species, or combinations thereof. It should be noted that any component provided hereunder can be provided, where valence and stability permit, in an ionic form, in a protonated or unprotonated form, in salt or free base form, or as ionic or covalent substituents in combination with other components that hydrolyze and make the component available in aqueous solutions, as suitable and appropriate. 
     In certain embodiments, the runtime perfusion solution contains buffering components. For example, suitable buffer systems include 2-morpholinoethanesulfonic acid monohydrate (IVIES), cacodylic acid, H 2 CO 3 /NaHCO 3  (pK a1 ), citric acid (pK a3 ), bis(2-hydroxyethyl)-imino-tris-(hydroxymethyl)-methane (Bis-Tris), N-carbamoylmethylimidino acetic acid (ADA), 3-bis[tris(hydroxymethyl)methylamino]propane (Bis-Tris Propane) (pK a1 ), piperazine-1,4-bis(2-ethanesulfonic acid) (PIPES), N-(2-Acetamido)-2-aminoethanesulfonic acid (ACES), imidazole, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), 3-(N-morpholino)propanesulphonic acid (MOPS), NaH 2 PO 4 /Na 2 HPO 4  (pK a2 ), N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), N-(2-hydroxyethyl)-piperazine-N′-2-ethanesulfonic acid (HEPES), N-(2-hydroxyethyl)piperazine-N′-(2-hydroxypropanesulfonic acid) (HEPPSO), triethanolamine, N-[tris(hydroxymethyl)methyl]glycine (Tricine), tris hydroxymethylaminoethane (Tris), glycineamide, N,N-bis(2-hydroxyethyl) glycine (Bicine), glycylglycine (pK a2 ), N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid (TAPS), or a combination thereof. In some embodiments, the solutions contain sodium bicarbonate, potassium phosphate, or TRIS buffer. 
     The runtime perfusion solution can include other components to help maintain the liver and protect it against ischemia, reperfusion injury and other ill effects during perfusion. In certain exemplary embodiments these components can include hormones (e.g., insulin), vitamins (e.g., an adult multi-vitamin, such as multi-vitamin MVI-Adult), and/or steroids (e.g., dexamethasone and SoluMedrol). 
     In another aspect, a blood product can be provided with the runtime perfusion solution to support the liver during preservation. Exemplary suitable blood products can include whole blood, and/or one or more components thereof such as blood serum, plasma, albumin, and red blood cells. In embodiments where whole blood is used, the blood can be passed through a leukocyte and platelet depleting filter to reduce pyrogens, antibodies and/or other items that can cause inflammation in the organ. Thus, in some embodiments, the perfusion fluid employs whole blood that has been at least partially depleted of leukocytes and/or whole blood that has been at least partially depleted of platelets. 
     The perfusion fluid comprising the blood product and the runtime perfusion solution can be provided at a physiological temperature and maintained thereabout throughout perfusion and recirculation. As used herein, “physiological temperature” is referred to as temperatures between about 25° C. and about 37° C., for example, between about 30° C. and about 37° C., such as between about 34° C. and about 37° C. 
     Other components or additives can be added to the runtime perfusion solution, including, for example, adenosine, magnesium, phosphate, calcium, and/or sources thereof. In some embodiments, additional components are provided to assist the liver in conducting its metabolism during perfusion. These components include, for example, forms of adenosine, which can be used for ATP synthesis, for maintaining endothelial function, and/or for attenuating ischemia and/or reperfusion injury. Components can also include other nucleosides, such as guanosine, thymidine ( 5 -Me-uridine), cytidine, and uridine, as well as other naturally and chemically modified nucleosides including nucleotides thereof. According to some embodiments, a magnesium ion source is provided with a phosphate source, and in certain embodiments, with adenosine to further enhance ATP synthesis within the cells of the perfused liver. A plurality of amino acids can also be added to support protein synthesis by the liver cells. Applicable amino acids can include, for example, any of the naturally-occurring amino acids, as well as those mentioned above. 
     In some embodiments, the runtime perfusion solution further comprises one or more vasodilators (e.g., a vasodilator can be used to increase or decrease vascular tone and thereby the pressure within the vessel). In some particular embodiments, the vasodilator used is Flolan® although other vasodilators can also be used. 
     Table 2 sets forth components that can be used in a runtime perfusion solution for preserving a liver as described herein. The runtime perfusion solution can include one or more of the components described in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Component of Exemplary Composition 
               
               
                 for the Runtime Perfusion Solution 
               
            
           
           
               
               
            
               
                   
                 Exemplary Concentration Ranges in 
               
               
                 Component 
                 Preservative Solution 
               
               
                   
               
               
                 Alanine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Arginine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Asparagine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Aspartic Acid 
                 about 1 mg/L-about 10 g/L 
               
               
                 Cysteine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Cystine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Glutamic Acid 
                 about 1 mg/L-about 10 g/L 
               
               
                 Glutamine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Glycine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Histidine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Hydroxyproline 
                 about 1 mg/L-about 10 g/L 
               
               
                 Isoleucine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Leucine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Lysine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Methionine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Phenylalanine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Proline 
                 about 1 mg/L-about 10 g/L 
               
               
                 Serine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Threonine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Tryptophan 
                 about 1 mg/L-about 10 g/L 
               
               
                 Tyrosine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Valine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Adenine 
                 about 1 mg/L-about 10 g/L 
               
               
                 ATP 
                 about 10 ug/L-about 100 g/L 
               
               
                 Adenylic Acid 
                 about 10 ug/L-about 100 g/L 
               
               
                 ADP 
                 about 10 ug/L-about 100 g/L 
               
               
                 AMP 
                 about 10 ug/L-about 100 g/L 
               
               
                 Ascorbic Acid 
                 about 1 ug/L-about 10 g/L 
               
               
                 D-Biotin 
                 about 1 ug/L-about 10 g/L 
               
               
                 Vitamin D-12 
                 about 1 ug/L-about 10 g/L 
               
               
                 Cholesterol 
                 about 1 ug/L-about 10 g/L 
               
               
                 Dextrose (Glucose) 
                 about 1 g/L-about 150 g/L 
               
               
                 Multi-vitamin Adult 
                 about 1 mg/L-about 20 mg/L or 1 unit vial 
               
               
                 Epinephrine 
                 about 1 ug/L-about 1 g/L 
               
               
                 Folic Acid 
                 about 1 ug/L-about 10 g/L 
               
               
                 Glutathione 
                 about 1 ug/L-about 10 g/L 
               
               
                 Guanine 
                 about 1 ug/L-about 10 g/L 
               
               
                 Inositol 
                 about 1 g/L-about 100 g/L 
               
               
                 Riboflavin 
                 about 1 ug/L-about 10 g/L 
               
               
                 Ribose 
                 about 1 ug/L-about 10 g/L 
               
               
                 Thiamine 
                 about 1 mg/L-about 10 g/L 
               
               
                 Uracil 
                 about 1 mg/L-about 10 g/L 
               
               
                 Calcium Chloride 
                 about 1 mg/L-about 100 g/L 
               
               
                 NaHCO 3   
                 about 1 mg/L-about 100 g/L 
               
               
                 Magnesium sulfate 
                 about 1 mg/L-about 100 g/L 
               
               
                 Potassium chloride 
                 about 1 mg/L-about 100 g/L 
               
               
                 Sodium glycerophosphate 
                 about 1 mg/L-about 100 g/L 
               
               
                 Sodium Chloride 
                 about 1 mg/L-about 100 g/L 
               
               
                 Sodium Phosphate 
                 about 1 mg/L-about 100 g/L 
               
               
                 Insulin 
                 about 1 IU-about 150 IU 
               
               
                 Serum albumin 
                 about 1 g/L-about 100 g/L 
               
               
                 Pyruvate 
                 about 1 mg/L-about 100 g/L 
               
               
                 Coenzyme A 
                 about 1 ug/L-about 10 g/L 
               
               
                 Serum 
                 about 1 ml/L-about 100 ml/L 
               
               
                 Heparin 
                 about 500 U/L-about 1500 U/L 
               
               
                 Solumedrol 
                 about 200 mg/L-about 500 mg/L 
               
               
                 Dexamethasone 
                 about 1 mg/L-about 1 g/L 
               
               
                 FAD 
                 about 1 ug/L-about 10 g/L 
               
               
                 NADP 
                 about 1 ug/L-about 10 g/L 
               
               
                 guanosine 
                 about 1 mg/L-about 10 g/L 
               
               
                 GTP 
                 about 10 ug/L-about 100 g/L 
               
               
                 GDP 
                 about 10 ug/L-about 100 g/L 
               
               
                 GMP 
                 about 10 ug/L-about 100 g/L 
               
               
                   
               
            
           
         
       
     
     Table 3 sets forth components that can be used in an exemplary runtime perfusion solution. The amounts provided in Table 3 describe preferred amounts relative to other components in the table and can be scaled to provide compositions of sufficient quantity. In some embodiments, the amounts listed in Table 3 can vary by ±about 10% and still be used in the solutions described herein. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Components of Exemplary Runtime Perfusion Solution 
               
            
           
           
               
               
            
               
                 Component 
                 Amount 
               
               
                   
               
               
                 Calcium Chloride dihydrate 
                 About 2100 mg-About 2600 mg 
               
               
                 Glycine 
                 About 315 mg-About 385 mg 
               
               
                 L-Alanine 
                 About 150 mg-About 200 mg 
               
               
                 L-Arginine 
                 About 600 mg-About 800 mg 
               
               
                 L-Aspartic Acid 
                 About 220 mg-About 270 mg 
               
               
                 L-Glutamic Acid 
                 About 230 mg-About 290 mg 
               
               
                 L-Histidine 
                 About 200 mg-About 250 mg 
               
               
                 L-Isoleucine 
                 About 100 mg about 130 mg 
               
               
                 L-Leucine 
                 About 300 mg-About 380 mg 
               
               
                 L-Methionine 
                 About 50 mg-About 65 mg 
               
               
                 L-Phenylalanine 
                 About 45 mg-About 60 mg 
               
               
                 L-Proline 
                 About 110 mg-About 140 mg 
               
               
                 L-Serine 
                 About 80 mg-About 105 mg 
               
               
                 L-Thereonine 
                 About 60 mg-About 80 mg 
               
               
                 L-Tryptophan 
                 About 30 mg-About 40 mg 
               
               
                 L-Tyrosine 
                 About 80 mg-About 110 mg 
               
               
                 L-Valine 
                 About 150 mg-About 190 mg 
               
               
                 Lysine Acetate 
                 About 200 mg-About 250 mg 
               
               
                 Magnesium Sulfate Heptahydrate 
                 About 350 mg-About 450 mg 
               
               
                 Potassium Chloride 
                 About 15 mg-About 25 mg 
               
               
                 Sodium Chloride 
                 About 1500 mg-About 2000 mg 
               
               
                 Dextrose 
                 About 25 gm-About 120 gm 
               
               
                 Epinephrine 
                 About 0.25 mg-About 1.0 mg 
               
               
                 Insulin 
                 About 75 Units-About 150 Units 
               
               
                 MVI-Adult 
                 1 unit vial 
               
               
                 SoluMedrol 
                 About 200 mg-500 mg 
               
               
                 Sodium Bicarbonate 
                 About 10-25 mEq 
               
               
                   
               
            
           
         
       
     
     In the exemplary embodiment of a runtime perfusion solution, the components in Table 3 can be combined in the relative amounts listed therein per about 1 L of aqueous fluid to form the runtime perfusion solution. In some embodiments, the quantity of aqueous fluid in the runtime perfusion solution can vary ±about 10%. The pH of the runtime perfusion solution can be adjusted to be between about 7.0 and about 8.0, for example about 7.3 and about 7.6. The runtime perfusion solution can be sterilized, for example by autoclaving, to provide for improved purity. 
     Table 4 sets forth another exemplary runtime perfusion solution, comprising a tissue culture media having the components identified in Table 4 and combined with an aqueous fluid, which can be used in the perfusion fluid as described herein. The amounts of components listed in Table 4 are relative to each other and to the quantity of aqueous solution used. In some embodiments, about 500 mL of aqueous fluid is used. In some embodiments, the quantity of aqueous solution can vary ±about 10%. The component amounts and the quantity of aqueous solution can be scaled as appropriate for use. The pH of the runtime perfusion solution, in this embodiment, can be adjusted to be about 7.0 to about 8.0, for example about 7.3 to about 7.6. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Composition of Another Exemplary Runtime Perfusion 
               
               
                 Solution (about 500 mL aqueous solution) 
               
            
           
           
               
               
               
               
            
               
                   
                 Tissue Culture Component 
                 Amount 
                 Specification 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Calcium Chloride dihydrate 
                 2400 
                 mg 
                 ±about 10% 
               
               
                   
                 Glycine 
                 350 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Alanine 
                 174 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Arginine 
                 700 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Aspartic Acid 
                 245 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Glutamic Acid 
                 258 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Histidine 
                 225 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Isoleucine 
                 115.5 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Leucine 
                 343 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Methionine 
                 59 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Phenylalanine 
                 52 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Proline 
                 126 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Serine 
                 93 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Thereonine 
                 70 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Tryptophan 
                 35 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Tyrosine 
                 92 
                 mg 
                 ±about 10% 
               
               
                   
                 L-Valine 
                 171.5 
                 mg 
                 ±about 10% 
               
               
                   
                 Lysine Acetate 
                 225 
                 mg 
                 ±about 10% 
               
               
                   
                 Magnesium Sulfate Heptahydrate 
                 400 
                 mg 
                 ±about 10% 
               
               
                   
                 Potassium Chloride 
                 20 
                 mg 
                 ±about 10% 
               
               
                   
                 Sodium Chloride 
                 1750 
                 mg 
                 ±about 10% 
               
               
                   
                   
               
            
           
         
       
     
     Since amino acids are the building blocks of proteins, the unique characteristics of each amino acid impart certain important properties on a protein such as the ability to provide structure and to catalyze biochemical reactions. The selection and concentrations of the amino acids provided in the runtime perfusion solutions can provide support of normal physiologic functions such as metabolism of sugars to provide or store energy, regulation of protein metabolism, transport of minerals, synthesis of nucleic acids (DNA and RNA), regulation of blood sugar and support of electrical activity, in addition to providing protein structure. Additionally, the concentrations of specific amino acids found in the runtime perfusion solution can be used to predictably stabilize the pH of the runtime perfusion solution. 
     In certain embodiments, in order to prevent the blood used as part of the perfusion fluid for preserving the liver on the organ care system  600  from clotting during preservation, anti-clotting agents can be added to the runtime perfusion solution as additives. Non-limiting examples of anti-clotting agents include heparin. In some embodiments, heparin can be included in a sufficient amount to prevent clotting for 500-600 seconds, although other times are possible. 
     In certain embodiments, the runtime perfusion solution includes a plurality of amino acids. In certain embodiments, the runtime perfusion solution includes electrolytes, such as calcium and magnesium. 
     In one embodiment, a runtime perfusion solution includes one or more amino acids, and one or more carbohydrates, such as glucose or dextrose. The runtime perfusion solution can also have additives, such as those described herein, administered at the point of use just prior to infusion into the liver perfusion system. For example, additional additives that can be included with the solution or added at the point of use by the user include hormones and steroids, such as dexamethasone and insulin, as well as vitamins, such as an adult multi-vitamin, for example adult multivitamins for infusion, such as MVI-Adult. Additional small molecules and large bio-molecules can also be included with the runtime perfusion solution or added at the point of use by the user, including therapeutics and/or components typically associated with blood or blood plasma, such as albumin. 
     In some embodiments, therapeutics can be added either before or during perfusion of the liver. The therapeutics can also be added directly to the system independently from the runtime perfusion solution, before or during perfusion of the organ. 
     With further reference to Table 3 or 4, certain components used in the exemplary runtime perfusion solution are molecules, such as small organic molecules or large biomolecules, that would be inactivated, for example through decomposition or denaturing, if passed through sterilization. Thus, these components can be prepared separately from the remaining components of the runtime perfusion solution. The separate preparation involves separately purifying each component through known techniques. The remaining components of the runtime perfusion solution are sterilized, for example through an autoclave, then combined with the biological components. 
     Table 5 lists certain biological components that can be separately purified and added to the solutions (runtime perfusion solution and/or priming solution) described herein after sterilization, according to this two-step process. These additional or supplemental components can be added to runtime perfusion solution, the priming solution or a combination thereof individually, in various combinations, all at once as a composition, or as a combined solution. For example, in certain embodiments, the insulin, and MVI-Adult, listed in Table 5, are added to the runtime perfusion solution. In another example, the SoluMedrol and the sodium bicarbonate, listed in Table 5, are added to the priming solution. The additional components can also be combined in one or more combinations or all together and placed in solution before being added to runtime perfusion solution, and/or the priming solution. In some embodiments, the additional components are added directly to the perfusion fluid. The component amounts listed in Table 5 are relative to each other and/or to the amounts of components listed in one or more of Tables 1-4 as well as the amount of aqueous solution used in preparing the runtime perfusion solution, and/or the priming solution and can be scaled as appropriate for the amount of solution required. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Exemplary Biological Components Added to Solutions Prior to Use 
               
            
           
           
               
               
               
               
            
               
                 Component 
                 Amount 
                 Type 
                 Specification 
               
               
                   
               
               
                 Insulin 
                 about 100 Units 
                 Hormone 
                 ±about 10% 
               
               
                 MVI-Adult 
                 1 mL unit vial 
                 Vitamin 
                 ±about 10% 
               
               
                 SoluMedrol 
                 About 250 mg 
                 Steroid 
                 ±about 10% 
               
               
                 Sodium Bicarbonate 
                 About 20 mEq 
                 Buffer 
                 ±about 10% 
               
               
                   
               
            
           
         
       
     
     In one embodiment, a composition for use in a runtime perfusion solution is provided comprising one or more carbohydrates, one or more organ stimulants, and a plurality of amino acids. The composition can also include other substances, such as those used in solutions described herein. 
     In another embodiment, a system for perfusing a liver, is provided comprising a liver and a substantially cell-free composition, comprising one or more carbohydrates, one or more organ stimulants, and a plurality of amino acids. The substantially cell-free composition can include systems that are substantially free from cellular matter; in particular, systems that are not derived from cells. For example, substantially cell-free composition can include compositions and solutions prepared from non-cellular sources. 
     In another aspect, the runtime perfusion solution and/or the priming solution can be provided in the form of a kit that includes one or more organ maintenance solutions. An exemplary runtime perfusion solution can include components identified above in one or more fluid solutions for use in a liver perfusion fluid. In certain embodiments, the runtime perfusion solution can include multiple solutions which, in various combinations, provide the runtime perfusion solution. Alternatively, the kit can include dry components that can be regenerated in a fluid to form one or more runtime perfusion solution or priming solution. The kit can also comprise components from the runtime perfusion solution or priming solution in one or more concentrated solutions which, on dilution, provide a preservation, nutritional, and/or supplemental solution as described herein. The kit can also include a priming solution. 
     In certain embodiments, the kit is provided in a single package, wherein the kit includes one or more solutions (or components necessary to formulate the one or more solutions by mixing with an appropriate fluid), and instructions for sterilization, flow and temperature control during perfusion and use and other information necessary or appropriate to apply the kit to organ perfusion. In certain embodiments, a kit is provided with only a single runtime perfusion solution (or set of dry components for use in a solution upon mixing with an appropriate fluid), and along with a set of instructions and other information or materials necessary or useful to operate the runtime perfusion solution or priming solution. 
     In certain embodiments, the runtime perfusion solution is a singular solution. In other embodiments, the runtime perfusion solution can include a main runtime perfusion solution and one or more nutritional supplement solutions. The nutritional supplement solution can contain any compound or biological component suitable for the runtime perfusion describe above. For instance, the nutritional supplement solution can contain one or more components illustrated in Tables 1-5 above. Additionally, Table 6 sets forth components that are used in an exemplary nutritional supplement solution. In some embodiments, the nutritional solution further includes sodium glycerol phosphate. The amount of components in Table 6 is relative to the amount of aqueous solvent employed in the solution (about 500 mL) and may be scaled as appropriate. In some embodiments, the quantity of aqueous solvent varies ±about 10%. In these embodiments when a main runtime solution and one or more nutritional solutions are used, these solutions can be separately connected to the circulation system of the organ care system  600  and control separately. Thus, when one or more components in a nutritional solution need to be adjusted, the operator may remake this particular nutritional solution with different concentration for these components or adjust only the flow rate and/or pressure for this nutritional solution without affecting the flow rate and/or pressure for the main runtime perfusion solution and other nutritional solutions. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Components of Exemplary Nutritional Solution (about 500 mL) 
               
            
           
           
               
               
               
               
            
               
                   
                 Component 
                 Amount 
                 Specification 
               
               
                   
                   
               
               
                   
                 Dextrose 
                 40 g. 
                 ±about 10%. 
               
               
                   
                   
               
            
           
         
       
     
     In one embodiment, the runtime perfusion solution and the priming solution have the identical composition which is described in any one of Tables 1-6 or a combination thereof. 
     In some embodiments, the perfusion liquid comprises 1200-1500 ml of pRBCs, 400 ml of 25% Albumin, 700 ml of PlasmaLyte, antibiotic (gram positive and gram negative) 1 g Cefazoline (or equivalent antibiotic) and 100 mg Cipro (or equivalent antibiotic), 500 mg of Solu-Medrol (or equivalent anti-inflammatory), 50 mmol Hco3, multivitamin, and 10000 unit of Heparin administered at 3 hr and 6 hr PT. 
     In certain specific embodiments, the perfusion fluid comprises the liver donor&#39;s blood, or packed red blood cells (RBCs), or packed RBCs with fresh frozen plasma, and the runtime perfusion solution containing one or more components selected form the group consisting of human albumin or dextran. In certain specific embodiments, the perfusion fluid comprises the liver donor&#39;s blood, or packed RBCs or packed RBCs with fresh frozen plasma, and the runtime perfusion solution containing one or more components selected form the group consisting of human albumin, dextran, and one or more electrolyte. 
     E. Final-Flush Solution 
     After the suitable recipient of the liver transplant is identified and before the liver is removed from the organ care system  600 , the liver organ can be subjected to another flush process by a flush solution. This flush solution has the similar function as the initial flush solution, which is to remove the residual blood therein and stabilize the liver. This flush solution is referred to herein as the final flush solution. In some embodiments, the final flush solution has similar or identical compositions as the initial flush solution described above. The main components of the final flush solution can include electrolytes (e.g., plasmalyte) and buffering agents described herein. In certain embodiments, one or more commercially available preservation solutions used in hypothermal organ transplant are used as the final flush solution. After the liver is subjected to the final flush and cooled according to one more embodiments described herein, the liver can be removed from the organ care system  600  for implantation into a recipient. 
     VI. Methods 
     Exemplary methods to use the organ care system  600  disclosed herein are now described in more detail.  FIG. 29  is a flow diagram  5000  depicting exemplary and non-limiting methodologies for harvesting the donor liver and cannulating it into the organ care system  600  described herein. The process  5000  shown in  FIG. 29  is exemplary only and can be modified. For example, the stages described therein can be altered, changed, rearranged, and/or omitted. 
     A. Harvesting Organ 
     As shown in  FIG. 29 , the process of obtaining and preparing liver for cannulation and transport can begin by providing a suitable liver donor (Stage  5004 ). The system  600  can be brought to a donor location, whereupon the process of receiving and preparing the donor liver for cannulation and preservation can proceed down pathways  5006  and  5008 . The pathway  5006  principally involves preparing the donor liver for preservation, while the pathway  5008  principally involves preparing the system to receive and preserved the liver, and then transport the liver via the organ care system  600  to the recipient site. 
     As shown in  FIG. 29 , the first pathway  5006  can include exsanguinating the donor blood (Stage  5010 ), explanting the liver (Stage  5014 ), flushing the liver with initial flush solution (Stage  5016 ), and preparing and cooling the liver for the system (Stage  5018 ). In particular, in the exsanguination stage  5010 , the donor&#39;s blood can be partially and/or wholly removed and set aside so it can be used to as the blood product in the perfusion liquid to perfuse the liver during preservation on the system. This stage can be performed by inserting a catheter into either the arterial or venous vasculature of the donor to allow the donor&#39;s blood to flow out of the donor and be collected into a blood collection bag. The donor&#39;s blood is allowed to flow out until the necessary amount of blood is collected, typically 1.0-2.5 liters, whereupon the catheter is removed. The blood extracted through exsanguination is then optionally filtered and added to a fluid reservoir of the system in preparation for use with the system. Alternatively, the blood can be exsanguinated from the donor and filtered for leukocytes and platelets in a single step that uses an apparatus having a filter integrated with the cannula and blood collection bag. An example of such a filter is a Pall BC2B filter. Alternatively, a blood product can be used instead of the donor&#39;s blood in the perfusion liquid (not shown in  FIG. 29 ). 
     After the donor&#39;s blood is exsanguinated, the donor liver can be harvested (Stage  5014 ). Any standard liver harvesting method known in the art can be used. During liver harvesting, the liver vessels including hepatic artery, portal vein, inferior vena cava (IVC), and bile duct are prepared properly and severed, with sufficient vessel length remained for cannulation (e.g., standard practice, suitable for human or animal transplant). In certain embodiments, the gall bladder is removed during the liver harvesting and care is taken to preserve the common bile duct intact to maintain stable bile fluid flow during the liver preservation. After the liver is removed in hospital settings, it is often flushed (e.g., donor flush) or placed in saline solutions. In stage  5016 , the harvested liver can then be flushed by an initial flush solution to remove any residual blood and/or donor flush solution to improve the stability of the liver. An exemplary composition of the initial flush solution is described above in detail. 
     After the liver is harvested and prior to its placement on the organ care system  600 , the liver can be cooled down (Stage  5018 ) to reduce or halt its metabolic functions to avoid damage to the liver which otherwise can occur during transportation or placement of the liver into the organ care system  600 . In certain embodiments, the liver is cooled to about 4° C. to 10° C., 5° C. to 9° C., 5° C. to 8° C., 4° C., 5° C., 6° C., 7° C., 8° C., 9° C., or 10° C., or a temperature within any range bounded by the value described herein. The liver can be cooled by ice or refrigeration. Other temperature ranges below 4° C. and above 10° C. are also possible. Alternatively, the initial flush solution can be cooled first and then used to flush the liver to cool the liver. Thus, in these alternative embodiments, Stages  5016  and  5018  can be performed simultaneously. Once the liver is prepared and cooled to a proper temperature, it can be ready to be placed onto the liver care system  600 . 
     With continued reference to  FIG. 29 , during the preparation of the liver via path  5006 , the system can be prepared through the stages of path  5008  so it is primed and waiting to receive the liver for cannulation and preservation as soon as the liver is prepared and cooled. By quickly transferring the liver from the donor to the system, and subsequently perfusing the liver with the perfusion fluid, a medical operator can minimize the amount of time the liver is deprived of oxygen and other nutrients, and thus reduce ischemia and other ill effects that arise during current organ care techniques. In certain embodiments, the amount of time between infusing the liver with the initial flush solution and beginning flow of the perfusion fluid through the liver via the organ care system  600  is less than about 15 minutes. In other illustrative embodiments, the between-time is less than about ½ hour, less than about 1-hour, less than about 2 hours, or even less than about 3 hours. Similarly, the time between transplanting the liver into the organ care system  600  and bringing the liver to a near physiological temperature (e.g., between about 34° C. and about 37° C.) can occurs within a brief period of time so as to reduce ischemia within the liver tissues. In some illustrative embodiments, the period of time is less than about 5 minutes, while in other applications it can be less than about ½ hour, less than about 1-hour, less than about 2 hours, or even less than about 3 hours. Stated differently, when the cooled liver is first placed into the organ care system  600 , the temperature of the liver can gradually be raised to the desired temperature over a predetermined amount of time to reduce any potential damage that could result of a sudden temperature change. 
     As shown in  FIG. 29 , the system can be prepared in pathway  5008  through a series of stages, which include preparing the single use module (stage  5022 ), priming the system with priming solution (stage  5024 ), filtering the blood from the donor and adding it to the system, e.g., at a reservoir of the system (stage  5012 ), optionally priming the system with blood and/or perfusion fluids, and connecting the liver into the system (stage  5020 ). In particular, the step  5022  of preparing the single use module includes assembling the disposable single use module described herein (e.g., single use module  634 ). After the single use module is assembled, or provided in the appropriate assembly, it is then inserted into and connected to the multiple use module (e.g., multiple use module  650 ) through the process described herein. 
     Specifically, in stage  5024 , the liver care system  600  can be first primed with a priming solution, the composition of which is described more fully above. In certain embodiments, to aid in priming, the system can provide an organ bypass conduit installed into the organ chamber assembly. For example, in certain specific embodiments, the bypass conduit includes three segments attached to the hepatic artery cannulation interface, the portal vein cannulation interface, and the inferior vena cava (IVC) cannulation interface (if present). Using the bypass conduit attached/cannulated into the liver chamber assembly, an operator can cause the system to circulate the perfusion fluid through all of the paths used during actual operation. This can enable the system to be thoroughly tested and primed prior to cannulating the liver into place. 
     In stage  5012 , blood from the donor can be filtered and added to the system, e.g., in the reservoir  160 . The filtering process can help reduce the inflammatory process through the complete or partial removal of leukocytes and platelets. Additionally, the donor blood can be used to optionally prime the system as described above and/or mixed with one or more priming solution or runtime perfusion solution to further prime the system as described above. Additionally, the blood and the run time perfusion solution can be mixed together to form the perfusion fluid used later for infusing and preserving the liver. In stage  5026 , the system can be primed with the blood and/or the perfusion fluid by activating the pump and by pumping the blood and/or the perfusion fluid through the system with the bypass conduit (described above) in place. As the perfusion fluid circulates through the system in priming stage  5026 , it can optionally be warmed to the desired temperature (e.g., normothermic) as it passes through a heater assembly of the system. Thus, prior to cannulating the harvested liver, the system can be primed by circulating the priming solution, exsanguinated donor blood, and/or the mixture of the two (e.g., the perfusion fluid) through the system to heat, oxygenate and/or filter it. Nutrients, preservatives, and/or other therapeutics can also be provided during priming by addition of the components to the priming solution. During priming, various parameters can also be initialized and calibrated via the operator interface during priming. Once primed and running appropriately, the pump flow can be reduced or cycled off, the bypass conduit can be removed from the organ chamber assembly, and the liver can then be cannulated into the organ chamber assembly. 
     1. Cannulation 
     In stage  5020 , the liver, while cooled as described above, can be cannulated and placed onto the organ care system  600 . During liver preservation, the perfusion fluid can flow into the liver through the hepatic artery and portal vein and flow out of the liver through the inferior vena cava (IVC). Thus, the hepatic artery, inferior vena cava (IVC), and portal vein can be correspondingly cannulated and connected with the relevant flow path of the liver care system  600  to ensure proper perfusion through the liver (as described above). In some embodiments, the IVC is not cannulated and free drains. The bile duct can also be cannulated as well and connected to a reservoir to collect the bile produced by the liver (e.g., bile bag  187 ). 
     The system  600  described herein can be designed to be compatible with the human hepatic artery anatomy. In the majority of the patients, the hepatic artery is the only major artery of the liver and thus the organ care system  600  can a single-port cannula to be connected with the hepatic artery. In certain cases (e.g., about 10-20% of the patient population with genetic difference), however, the donor of the liver also has an accessory hepatic artery in addition to the main hepatic artery. Thus, in certain embodiments, the liver care system  600  provides a dual-port cannula configuration (e.g., cannula  2642 ) so that both the main and accessory hepatic arteries can be cannulated and connected to the same perfusion fluid flow path. In certain specific embodiments, the dual-port cannula has a Y shape. Any other suitable shapes or designs for the dual-port cannula are contemplated. 
     In certain embodiments, the cannula can be designed to be straight to reduce unnecessary flow pressure drop along the cannula flow path. In other embodiments, the cannula can be designed to be curved or angled as required by the shape, size, or geometry of the organ care system  600 &#39;s other components. In some specific embodiments, the cannula is designed with a proper shape, e.g., straight, angled, or a combination thereof, so that the overall flow pressure within the cannula is maintained at a desired level that mimics physiologic conditions. 
     2. Instrumentation 
     The liver can then be instrumented on the organ care system  600  (Stage  5020 ) and more specifically, in the organ chamber  104 . Care should be taken to avoid excessive movement of the liver during instrumentation to reduce injuries to the liver. As described above in greater detail, the liver chamber can be specially designed to maintain the liver in a stable position that reduces its movement. 
     B. Preservation/Transport 
     1. Controlled Early Perfusion and Rewarming 
     In certain embodiments, once the liver is instrumented on the organ care system  600  with proper cannulation of the vessels, the liver can be subjected to an early perfusion and/or rewarm process to restore the liver to a normothermic temperature (34-37° C.) (Stage  5021 ). In some embodiments, the organ chamber can contain heating circuit to warm the previously cooled liver to normothermic temperature gradually over a predetermined amount of time. In other embodiments, the initial perfusion fluid (for early perfusion) can be heated to close to or to the normothermic temperature (e.g., 34-37° C.) and perfuse and warm the liver at the same time. As described herein, the liver preserved on the organ care system  600  can be kept at conditions near to physiological state, which includes normothermic temperatures, to maintain the liver&#39;s normal biological functions. 
     After the liver is instrumented onto the system and warmed to normothermic temperature, the pump within the organ care system  600  (e.g., pump  106 ) can be adjusted to pump perfusion fluid through the liver, e.g., into the hepatic artery and portal vein. The perfusion fluid exiting from the IVC (or hepatic veins, depending on how the liver was harvested) can be collected and subjected to various treatments including re-oxygenation and carbon dioxide removal. Various nutrients can be added to the spent perfusion fluid to increase the nutrient concentrations to required value for recirculation. 
     In some embodiments, during the liver perfusion on the organ care system  600 , the in-flow pressures within the hepatic artery and the portal vein are carefully controlled to ensure the proper delivery of nutrients to the liver to maintain its functions. In some embodiments, the flow pressure within the hepatic artery can be, for example, 50-120 mmHg and the flow pressure in the portal vein can be 5-15 mmHg, although pressures outside these ranges are possible such as 1, 2, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120 mmHg, or a pressure in any range bounded by the values noted here. In some embodiments, the flow rate within the hepatic artery and the portal vein can be maintained at about or more than 0.25-1.0 L/min, and 0.75-2.0 L/min, respectively, or at any range bounded by any of the values noted here. In some embodiments, the flow rate within the hepatic artery and the portal vein can be maintained at about 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.1, 2.2, 2.3, 2.4, 2.5 L/min or a rate in any range bounded by the values noted here. 
     In some embodiments, the fluid flow, e.g., flow rate and/or flow pressure, within the organ care system  600  and hepatic artery and the portal vein can be controlled chemically and/or mechanically. The mechanical or the chemical control of the flow can be achieved automatically or manually. 
     2. Manual/Automatic Control 
     The mechanical control of the fluid flow within the organ care system  600  and hepatic artery and the portal vein is first described. In some embodiments, the flow pressure or rate within the flow path of the organ care system  600  can be measured by pressure sensors or rate sensors built in the flow path or in other locations of the systems. Similarly, pressure or rate sensors can be located in the cannulas for the hepatic artery and/or the portal vein, or in the connectors connecting the cannulas to these vessels. The pressure or rate sensors can provide the operator with readings regarding the flow within the flow path and/or within the hepatic artery and/or the portal vein. Any other pressure monitoring methods or techniques known in the art are contemplated. If the pressure or rate reading is deviating from the desired values, the operator can manually adjust the flow pump to increase or decrease the pumping pressure and, thereby, the flow rate for the perfusion fluid. Alternatively, the organ care system  600  can contain a flow control module which has a programmable desired value for flow rate and/or flow pressure and automatically adjusts the pumping pressure of the perfusion fluid and thereby also adjusting the flow rate when the flow pressure and/or rate are deviating from the desired values. Manual and/or automatic control is described more fully above. 
     3. Chemical Control 
     In other embodiments, the pressure and/or fluid flow within the organ care system  600  and hepatic artery and the portal vein can be controlled chemically. In some specific embodiments, the pressure can be controlled or increased by using one or more vasodilators (e.g., a vasodilator can be used to increase or decrease vascular tone and thereby the pressure within the vessel). Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls. When blood vessels dilate, the flow of perfusion fluid is increased due to a decrease in vascular resistance. Any vasodilators known in the art can be used to dilate the hepatic artery and/or the portal vein to increase the fluid flow rate therein. In some particular embodiments, the vasodilator used is Flolan®. In particular, when the fluid flow is insufficient as indicated by low flow pressure or rate, and/or by any of the liver-viability evaluation techniques described in greater detail below, the operator can manually add vasodilator into the system&#39;s flow module or to the perfusion fluid to increase the fluid flow rate. Alternatively, the organ care system  600  can contain a flow control module which automatically adds one more vasodilators into the flow path or perfusion fluid to increase the flow rate. The amount of the vasodilator provided can be between, for example, 1-100 micrograms/hr, and more specifically between 1-5 micrograms/hr. These ranges are exemplary only and any range falling within 0-100 micrograms an hour can be used. 
     Some embodiments of the foregoing can be adapted for use with a liver that is being preserved in the system  600 . For example, in this embodiment, an algorithm can be used to allow closed loop control of the hepatic artery pressure (HAP). The algorithm used can be a proportional-integral-derivative controller (PID controller). A PID controller can calculate how far away the HAP is from the desired set point and attempt to minimize the error by increasing or decreasing the vasodilator (e.g., Flolan®) flow rate. 
     Accordingly, in some embodiments, the controller  150  (or other part of the system) can determine the error (e.g., how far the HAP is from the user set-point) and adjust the vasodilator flow rate in an attempt to make the error 0. In embodiments where the algorithm runs once a second the adjustments can be very small. Small, frequent adjustments can help to stabilize the control by ensuring that any noise in the system does not result in dramatic changes in vasodilator flow rate. The algorithm can be trying to get the HAP to the user set point. This means that when the HAP is above the set point the algorithm can increase the vasodilator solution flow rate until the HAP reaches the user set point. If the HAP is below the user set point the algorithm can decrease the vasodilator solution flow rate until the HAP reaches the user set point. 
     In some embodiments, the PID control algorithm does not decrease the vasodilator flow rate until it has gone under the set point. This can result in undershooting the target pressure. To help offset this, some embodiments can use a virtual set point, which is +3 mmHg (or other value) above the user set point. This can be user definable or hard programmed. When the HAP is higher than 7 mmHg above the user set point the software can enable the virtual set point and attempt to regulate the HAP to +3 mmHg above the user set point. This can allow for some undershoot of the virtual set point. Once the HAP has stabilized at the virtual set point the software can then regulate the HAP to the user set point. This approach can help “catch” the HAP as it is falling without incurring as dramatic of an undershoot. 
     Referring to  FIG. 28 , a graphical representation of the foregoing is shown with respect to ascending aortic pressure in a heart system. In  FIG. 28 , an exemplary graph  9500  of the foregoing is shown. The image shows the AOP (e.g.,  9505 ) coming down to a virtual set point ( 9510 ), undershooting the virtual set point and then coming down softly on the user set point (50 mmHg). 
     Because some embodiments use a drug to control the HAP it can be beneficial to ensure that the system is not flooding the liver with vasodilator when it is not needed. To accomplish this, the system can analyze how far the HAP is from the set point and when the HAP is above the set point, the system (e.g., the solution pump  631 ) can add vasodilator at the standard rate. If the HAP is below the set point, the system  600  can decrease the flow rate 4 times faster than if it were adding vasodilator. This can help the system stay just above the HAP set point (e.g., about +0.5 to +1 mmHg) in the “active management” area as well as potentially helping minimize undershoot but decreasing vasodilator rate faster. 
     While the foregoing description has focused on the liver, the same technique can be adapted for use with the heart by substituting AOP for the HAP. 
     4. Assessment 
     During stages  5028  and  5030  the operator can evaluate the liver functions to determine liver viability for transplant (then-current or likely future viability). Illustratively, step  5028  involves evaluating liver functions by using any of the evaluation techniques described in more detail below. For instance, the operator can monitor the fluid flows, pressures, and temperatures of the system while the liver is cannulated. The operator can also monitor one or more liver function biomarkers to assess the liver status. During the evaluation step  5030 , based on the data and other information obtained during testing  5028 , the operator can determine whether and how to adjust the system properties (e.g., fluid flows, pressures, nutrient concentrations, oxygen concentrations, and temperatures), and whether to provide additional modes of treatment to the liver (e.g., surgeries, medications as described in more detail below). The operator can make any such adjustments in step  5032 , can then repeat steps  5028  and  5030  to re-test and re-evaluate the liver and the system. In certain embodiments, the operator can also opt to perform surgical, therapeutic or other procedures on liver (described in more detail below) during the adjustment step  5032  (or at other times). For example, the operator can conduct an evaluation of the liver functions, such as for example, performing an ultrasound or other imaging test on the liver, measuring arterial and venous blood gas levels and other evaluative tests. 
     Thus, after or while the liver is preserved on the system, the operator can perform surgery on the liver or provide therapeutic or other treatment, such as immunosuppressive treatments, chemotherapy, genetic testing and therapies, or irradiation therapy. Because the system allows the liver to be perfused under near physiological temperature, fluid flow rate, and oxygen saturation levels, the liver can be maintained for a long period of time (e.g., for a period of at least 3 days or more, greater than at least 1 week, at least 3 weeks, or a month or more) to allow for repeated evaluation and treatment. 
     In some embodiments, the system allows a medical operator to evaluate the liver for compatibility with an intended recipient by identifying suitable recipient (Step  5034 ). For example, the operator can perform a Human Leukocyte Antigen (HLA) matching test on the liver while the liver is cannulated to the system. Such tests can require 12 hours or longer and are performed to ensure compatibility of the liver with the intended recipient. The preservation of a liver using the system described herein can allow for preservation times in excess of the time needed to complete an HLA match, potentially resulting in improved post-transplant outcomes. In the HLA matching test example, the HLA test can be performed on the liver while a preservation solution is pumping into the liver. Any other matching test known in the art is contemplated. 
     According to the illustrative embodiment, the testing  5028 , evaluation  5030  and adjustment  5032  stages can be conducted with the system operating in normal flow mode. In normal flow mode, the operator can test the function of the liver under normal or near normal physiologic blood flow conditions. Based on the evaluation  5030 , the settings of the system can be adjusted in step  5032 , if necessary, to modify the flow, heating and/or other characteristics to stabilize the liver in preparation for transport to the recipient site in stage  5036 . The system with the preserved liver can be transported to the recipient site at step  5036 . 
     C. Preparation for Transplant 
     1. Final Flush/Cool Liver 
     In certain embodiments, before the liver is removed from the system  600  and/or implanted into a recipient, the liver can be flushed by a final flush solution to, for example, remove any residual blood and/or runtime perfusion solution. The composition of the final flush solution is described in detail above. 
     In certain embodiments, prior to the removal of the liver from the organ care system  600 , the liver can be cooled again to a temperature at about 4° C. to 10° C., 5° C. to 9° C., 5° C. to 8° C., 4° C., 5° C., 6° C., 7° C., 8° C., 9° C., or 10° C., or a temperature within any range bounded by the value described herein. The liver can be cooled by contact with ice or refrigeration of the liver preservation chamber. In some embodiments, the system  600  can include a cooling unit that is configured to cool the liver directly and/or cool the fluid circulating in the system  100 . The final flush solution can also be chilled first and then used to flush the liver to cool the liver. Thus, in these embodiments, the liver can be finally flushed and cooled simultaneously. Once the liver is prepared and cooled down to a proper temperature, it can be ready to be transplanted into a suitable recipient. 
     For example, in some embodiments, the liver is cooled and flushed while on the system  600 . The user can connect a one liter bag of chilled flush solution to the flush port of the hepatic artery (e.g., port  4301 ) but leaves the port closed. The user connects two one-liter bags of chilled flush solution to the flush port of the portal vein (e.g., port  4302 ) but leaves the port closed. The user connects a flush collection bag to the perfusion module to the perfusate collection port located just after the perfusion module&#39;s pump compliance chamber (e.g., port  4309 ). The user can then apply a standard surgical clamp to the perfusion module tubing just before the split to the hepatic artery and portal vein simultaneous with the turning off of the circulatory pump  106 . The hepatic artery and portal vein flush ports can be opened so that the flush solution will enter the hepatic artery and the portal vein. The perfusate collection bag can be unclamped so that the mixture of perfusate and flush solution fills the bag rather than filling the organ chamber. 
     In the event that a decision is made to cool the liver at the end of preservation, then the following exemplary procedure can be used: 
     1. Obtain and set-up a Heater Cooler unit (placed near OCS, electrical line plugged in, power ON, water circuit controls ON, water circuit valve OFF). Do not connect Heater Cooler water lines to Liver Perfusion Module gas exchanger water lines yet. 
     2. Set Heater Cooler water circuit temperature to near the current liver temperature (e.g., approximately 37° C.) and allow it to reach temperature. 
     3. Connect Hansen quick connect equipped Heater Cooler water lines to Liver Perfusion Module oxygenator water lines. 
     4. Turn the heater  100  OFF. 
     5. Set water circuit temperature of Heater Cooler to a lower temperature than the liver but not more than 10° C. lower and open the valve of the water lines to allow flow to the Liver Perfusion Module gas exchanger  114 . As the actual temperature of the perfusion fluid, as reflected on the user interface, approaches the Heater Cooler water temperature set point, adjust the Heater Cooler water temperature set point lower, but not more than 10° C. lower than the perfusate/liver temperature, in increments and keep repeating until the blood/liver have reached the desired temperature. 
     6. When the liver temperature has reached the desired temperature, remove the liver from the system  600 . 
     While the foregoing has focused on final flush and cooling of a liver, a similar or identical procedure can be used when preserving other organs. For example, in some embodiments, the foregoing final flush/cooling technique can be applied to a heart and/or lung that is being preserved by the system  600 . 
     VII. Evaluation 
     In some embodiments of the disclosed subject matter, various techniques or methods to assess the viability of the liver while the liver is preserved on the organ care system  600  are provided (e.g., viability for transplant). Generally, biomarkers known in the art for evaluating liver functions, e.g., liver enzymes, and known imaging techniques can be used to evaluate the biological functions and status of the liver. Additionally, because the liver preserved on the organ care system  600  is readily accessible to the operator, techniques not easily available to the health care profession in vivo, e.g., visual observation of the liver or palpation of the liver, can also be used. Based on the evaluation results, one or more parameters of the organ care system  600 , e.g., nutrients or oxygen content in the perfusion fluid or the flow rate and flow pressure of the perfusion fluid, can be adjusted to improve the viability of the liver. 
     In some embodiments, the perfusion parameters of the organ care system  600  can be used to evaluate the viability of the liver. Specifically, in certain embodiments, the perfusion liquid flow pressures in the cannulated hepatic artery and/or portal vein can be measured as an indicator of the liver viability. In some embodiments, a stable flow pressure in the range of 50-120 mmHg in the hepatic artery line can indicate that the preserved liver is receiving sufficient essential nutrient supply. For example, in some embodiments, a stable flow pressure of about 50, 60, 70, 80, 90, 100, 110, 120 mmHg, or a pressure in any range bounded by the values noted here can indicate that the preserved liver is receiving sufficient essential nutrient supply. A flow pressure outside this range can indicate a leak or blockage in the system, or suggest to the operator to adjust the flow pressure to ensure proper nutrient supply to the liver. In other embodiments, the perfusion liquid flow rate in the cannulated hepatic artery and/or portal vein can be measured as an indicator of the liver viability. In other embodiments, a flow rate in the range of 0.25-1 L/min for the hepatic artery can indicate that the preserved liver is receiving sufficient essential nutrient supply. For example, in some embodiments, a flow rate of about 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00 L/min or a rate in any range bounded by the values noted here for the hepatic artery can indicate that the preserved liver is receiving sufficient essential nutrient supply. A flow rate outside this range can indicate a leak or blockage in the system, or suggest to the operator to adjust the flow rate to ensure proper nutrient supply to the liver. The flow rate and pressure can be measured using the pressure and/or flow sensors described herein. 
     In some embodiments, visual observation or examination of the liver can be used to assess the liver viability. For instance, a pink or red color of the liver can indicate that the liver is functioning normally, while a dark or blueish color of the liver can indicate that the liver is functioning abnormally or deteriorating (e.g., is being hypoperfused). In other embodiments, palpation of the liver is used to assess its viability. When the liver feels soft and elastic, the liver is likely functioning normally. On the other hand, if liver feels tense or stiff, the liver is likely functioning abnormally or deteriorating (e.g., is being hypoperfused). 
     A. Bile Production 
     In some embodiments, because the bile duct is cannulated and connected to a reservoir of the organ care system  600 , the color and amount of bile produced by the liver can be easily examined to evaluate the liver viability. In certain embodiments, black or dark green color bile can indicate normal liver function while a light or clear color of the bile can indicate that the liver is not functioning properly or deteriorating. In still other embodiments, the amount of the bile production can be used to evaluate the liver viability as well (and/or the determination that the liver is producing bile at all can be a good indicator). While any bile production can be a sign of a healthy liver, generally, the more the bile produced, the better the liver function. In certain embodiments, a bile production of from about 250 mL to 1 L, 500 mL to 1 L, 500 mL to 750 mL, 500 mL, 750, or 1 L per day or in any ranges bounded by the values noted herein suggests that the liver preserved on the organ care system  600  is functioning normally and viable. 
     B. Blood Gas, Liver Enzymes, and Lactate Measurements/Trends 
     In some embodiments, various biomarkers or compounds in the perfusion liquid can be used to evaluate the liver viability. For instance, metabolic assessment of the liver can be conducted by calculating oxygen delivery, oxygen consumption, and oxygen demand. Specifically, the amount of oxygen and carbon dioxide dissolved in the perfusion liquid can be monitored as indicators of the liver function. The concentrations of these gases in the perfusion liquid (or the blood product) before and after liver perfusion can be measured and compared. In certain specific embodiments, the concentrations of the oxygen and carbon dioxide can be measured by various sensors within the organ care system  600 &#39;s flow module or subsystem. 
     In some embodiments, the perfusion fluid before and after liver perfusion (e.g., the perfusion fluid entering the hepatic artery and exiting the IVC) can be sampled using respective oxygen concentration (or other) sensors and the relevant concentrations of the oxygen and carbon dioxide can be measured. A significant increase of the carbon dioxide concentration in the perfusion liquid after liver perfusion, and/or a significant decrease of the oxygen concentration after the liver perfusion, can indicate that the liver is performing its oxidative metabolic functions well. On the other hand, a minor or no increase of the carbon dioxide concentration in the perfusion liquid after liver perfusion, and/or minor or no decrease of the oxygen concentration after the liver perfusion, can indicate that the liver is not performing its oxidative metabolic functions properly. The difference of PvO 2  and PaO 2  can indicate metabolically active, aerobically active metabolism, oxygen consumption. 
     In some embodiments, liver function blood test (LEFTs) can be conducted to assess the liver viability. Specifically, in some embodiments, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphates, albumin, bilirubin (direct and indirect) can be measured to evaluate the liver functions. In other embodiments, the fibrinogen blood level can be measured as well as an indication of the liver cells&#39; ability to produce clotting factors. 
     AST, ALT are liver enzymes and are well-accepted clinical liver biomarkers used for assessing the liver functions and/or suitability for transplant. However, the measurements of AST and ALT are usually complicated and time-consuming, and are typically conducted in hospital or lab settings. Thus, there exists a need for a sensitive and simple indicator for determining the status of the preserved liver. Lactate, also called lactic acid, is a byproduct/end product of anaerobic metabolism in living cells/tissues/organs. Lactate is generated when there is no or low oxygen in the cell to metabolize glucose for basic energy production through the glycolysis pathway. Applicant has discovered that the level of the lactate in the perfusion liquid, e.g., the perfusion liquid exiting from the IVC, can be measured as a surrogate for measuring the AST levels. The lactate concentration can be measured quickly and simply, which provides significant advantages over the time-consuming liver enzyme measurement. Based on the quick feedback provided by lactate measurements, one or more parameters of the organ care system  600 , e.g., flow rate, pressure, and nutrient concentrations, can be adjusted to preserve or improve the liver viability quickly. Stated differently, lactate values (e.g., arterial lactate trends) can be correlated to and be indicative of AST levels. For example, a series (over time) of lactate measurements trending lower can correlate and/or be indicative of a trending lower AST. In some embodiments, lactate measurements can be taken in the measurement drain  2804 , although this is not required and can occur at any other location in the system  100 . Additionally, in some embodiments, the system  600  can be configured to obtain lactate measurements over time from a single location, a differential between a lactate value entering and exiting the liver, and over time at multiple locations. 
     C. Imaging 
     In still other embodiments, various other methods known in the art can be used to assess the liver viability. In some specific embodiments, ultrasound analysis of the liver can be conducted to assess liver parenchyma, intra- and extra-hepatic biliary tree. Other non-limiting examples of imaging techniques include Magnetic Resonance Imaging (MRI), Computed Tomography (CT), Positron Emission Tomography (PET), fluoroscopy, Transjugular Intrahepatic Portosystemic Shunt (TIPS), all of which can be used to assess the liver and detect abnormalities. For example, when examining an ultrasound of the liver, the doctor can examine sinusoidal dimensions, potential obstructions in the bile duct, and/or generalized blood flow. 
     D. Pathology/Biopsy 
     In still other embodiments, liver biopsy can be used to assess the liver viability. In liver biopsy, a small piece of liver tissue is removed so it can be examined under a microscope for signs of damage or disease. Because the liver is preserved ex vivo on the organ care system  600 , it is readily accessible and the biopsy can be easily conducted. 
     VIII. The Cloud 
     During operation, the system  600  generates information about the system itself and/or the organ being maintained. In some embodiments of the system  600 , this information can be stored in an internal memory such as RAM or ROM. In some embodiments the information generated by the system  600  can also be transmitted to a remote storage location such as in the Cloud. The Cloud can be, for example, a series of remote interconnected computers that are configured to provide data and/or services over the Internet. The Cloud can store the information, perform analysis on the information, and/or provide the information to one or more third parties and/or stakeholders. 
     In some embodiments of the system  600 , the system can include a multimodal communication link between itself and one of more other locations, such as servers in the Cloud. This communication link can be controlled by the controller  150  (e.g., via the data management subsystem  151 ), although this is not required and other components can be used to control communication. The controller  150  can be configured to provide real-time information about the system  600  and/or the organ contained therein to one or more remote locations while the system is at the donor hospital, is in transit, and/or is at the recipient hospital. In some embodiments, communication can be accomplished using communication link such as a wired network connection (e.g., Ethernet), a wireless network connection (e.g., IEEE 802.11), a cellular connection (e.g., LTE), a Bluetooth connection (e.g., IEEE 802.15), infrared connection, and/or a satellite-based network connection. In some embodiments, the controller  150  can maintain a priority list of connections favoring those connections which are more reliable such as a hardwired Internet connection and/or Wi-Fi over less reliable cellular and/or satellite connections. In other embodiments, the priority list can be generated with a preference for lower-cost transmission mediums such as Wi-Fi. 
     The system  600  can be configured to communicate with the Cloud, and ultimately remote parties via one or more techniques. For example, the system  600  can be configured to communicate with a server in the Cloud and/or directly with one or more remote computers. In some embodiments, the system  600  can be configured to: i) send communications such as emails and/or text messages to predetermined addresses, ii) upload data files to remote storage locations using, for example, FTP, iii) communicate with a dedicated remote server to provide information in a proprietary format, and iv) receive information downloaded from the Cloud and/or other remote computers. In some embodiments, the controller  150  can transmit/receive the information on a regular schedule, which can vary depending on which phase of operation the system is in. For example, the controller  150  can be configured to provide updates every five minutes while the system  600  is located at the donor hospital, every 15 seconds while in transport, and/or every 15 seconds while the system  600  is located at the receiving hospital. The controller  150  can also be configured to transmit/receive information in a secure manner, such as using encryption and/or with a timestamp. 
     The controller  150  can be configured to provide various types of information to the Cloud and/or remote location such as: an offer for an organ, system readiness information, battery charge level, gas tank level, status of the solution infusion pump, flow rates, pressure rates, oxygenation rates, hematocrit levels, lactate levels, temperature levels, the flow rate at which the pump  106  is set, the temperature at which the heater  110  is set, the position of the flow clamp  190 , some or all of the information displayed on the user interface (e.g., circulatory and infusion flow rates, pressures, oxygenation levels, hematocrit levels), geographic location, altitude, a copy of the displayed interface itself, waveforms displayed on the user interface, alarm limits, active alarms, screen captures of the user interface, photographs (e.g., captured using an onboard camera), HAP/HAF/Lacate trends, historical usage information about the system  600  (e.g., the number of hours it has been used), and/or donor information. In heart/lung embodiments additional information such as AOP and/or PEEP can be provided. Essentially, any piece of information that is collected, generated, and/or stored by the system  600  can be transmitted to the Cloud and/or a remote computer. 
     The controller  150  can be configured to receive various types of information from the Cloud and/or a remote location such as: instructions from a remote user, a “pull” demand for data from a remote location, control inputs, information about the organ recipient, and/or system updates. 
     In some embodiments, using the information provided by the system  600 , a user that is remote from the system  600  can effectively remotely view the same user interface that is displayed on the system  600 . Additionally, in some embodiments, a user that is remote to the system  600  can also remotely control the system  600  as if they were there in person. In some embodiments, the remote view can be an enhanced version of what is seen by the attending user. For example, the user interface can be presented in a similar format so that the remote user can visualize what the attending user sees, but the remote view can be enhanced so that it also displays additional information to provide context for the remote viewer. For example, donor demographics, geographic location, trends, and/or assessment results can also be displayed. A remote user can also be provided with virtual buttons and/or controls, matching those found on the system  600 , which can be used to remotely control operation of the system  600 . 
     In some embodiments, one or more technicians can remotely connect to and access the system  600  to perform diagnostics, update the system, and/or remotely troubleshoot issues. In some embodiments, remote technical assistance can be limited to times when the system  600  is not being used to preserve an organ. 
     In some embodiments, the information provided by the system  600  can be presented to a remote user through a web portal, mobile application, and/or other interface. 
     In some embodiments, access to the information provided by the system  600  can be limited to one or more registered users such as, surgical staff at the recipient hospital, a technical support team, and/or administrators. In some embodiments, access to information provided by the system  600  can be tied to an electronic medical file of the recipient. For example, the Cloud-based server can access one or more electronic medical files of the recipient to determine, for example: parties expressly identified as being able to have access to the recipient&#39;s health data, parties associated with organizations that are identified as being able to have access to the recipient&#39;s health data, and/or individuals working at medical facilities that are within a certain geographic distance of the recipient. 
     As described herein, sometimes during transport samples of perfusion fluid can be withdrawn for external analysis. In these instances, however, the data obtained through the external analysis is disassociated with the information contained within the system  600 . Thus, in some embodiments, the user interface provided by the system  600  can be configured to allow a user to input and store externally generated data about the organ. For example, if the attending user withdraws a sample of the perfusion fluid in order to perform a lactate measurement in an external analyzer, the attending user can then input and store the result in the system  600  along with the data that is generated by the system  600  itself. Along with the result itself, the user can also provide timestamp information and a description of the information. The information inputted by the user can be stored, processed, downloaded, and/or transmitted by the system  600  as if it were generated internally. In this manner, the system  600  can keep a complete record of all information relating to the organ while it was ex vivo regardless of whether the information was generated internally in or externally from the system  600 . 
     In operation, referring to  FIG. 26 , a process  6600  describes an exemplary embodiment of how the system  600  can be used with a Cloud-based communication/storage system. The process  6600  is exemplary only and not limiting. For example, the stages described therein can be altered, changed, rearranged, and/or omitted. The process  6600  assumes that the system  600  is in communication with a remote cloud-based server and that the system is being used to transport an organ, although this is not required. This process can be adapted to be used, for example, while an organ is being treated ex vivo for implantation back into the original patient rather than being transplanted into a new recipient. 
     At stage  6605 , an offer for an organ can be presented to the retrieval hospital by the organization that controls organ allocation (e.g., an organ procurement organization). Through a web portal to the system  600 , the retrieval hospital&#39;s staff can query the readiness (e.g., battery charge level, gas level) of the system  600  and can enter information about the donor. The information can be transferred to the system  600  via the server. 
     At stage  6610 , clinical support that have registered with the server as on-call staff can be alerted to the upcoming transport session via an email, a text message, an automated phone call, and/or any other communication means. The clinical support staff can be, for example, staff employed by the manufacturer of the system  600 . 
     At stage  6615 , which typically occurs during transport, the system  600  can transmit system/organ status information to a Cloud-based server via a communication link. The information transmitted to the server can be reviewed in an online portal by third parties such as the transplant surgeon, support staff, and/or any other permitted party (all of which can be at different geographic locations). In some embodiments, the server can perform additional processing on the information received from the system  600  to generate new information, which can then be presented back to the system  600  and/or to third parties. The information displayed to the user on the system  600  can be transmitted (e.g., either the underlying data and/or the image itself) to the server, for example, unsolicited once every 2 minutes. The data can then be stored with a timestamp on the server. For example, in some embodiments, each time information is received by the server from the system  600 , this can be placed in a row of an Excel spreadsheet. Additionally, during the stage  6615 , remote users that are viewing the information through the portal can “pull” (demand) a screen refresh/snapshot of the data from the OCS rather than waiting for the next 2-minute sample to be “pushed.” Additionally, in some embodiments, the remote parties can remotely control the operation of the system  600  via a remote interface. 
     The remote view can be an enhanced version of what is displayed on the monitor of the system  600 . It can be presented in a similar format so that the remote user can visualize what the attending user sees. In some embodiments, however, the remote view can also be enhanced so that it also displays additional information to provide context for the remote viewer, such as donor demographics, trends, and assessment results. 
     The system  600  can assert alerts through the server to remote third parties such as the transplant surgeon and/or clinical support team. The attending user can trigger contact from one of more remote third parties via a monitor menu action. For example, the attending user can send a request for assistance to technical support who can receive an alert via, for example, text message and/or email and call or otherwise contact the attending user. 
     The system  600  can automatically assert alerts in certain critical conditions (e.g., HAP&gt;120, or PVP&gt;20 mmHg). The attending user can also snap a photograph using a camera that is integrated into the system  600  (e.g., integrated into the operator interface module  146 ). The image can automatically be pushed to the server by the system  600 . 
     During stage  6615 , the system  600  can automatically provide information to the server and/or other remote computer at regular intervals such as every 15 seconds, every two minutes, every five minutes, or every 10 minutes. In some embodiments, information transmitted between the system  600 , the server, and/or the third party can occur in real time so that the remote party can have real time access to and/or control over the system  600  as if they were there in person. In some embodiments, the attending user and/or any other remote parties can initiate an unscheduled information transfer. In some embodiments, if the communication link of the system  600  has been disabled or is inoperable (e.g., during air transport), the controller  150  can be configured to continue generating regular status updates and store them for transmission once the communication link has been re-enabled. 
     At stage  6620 , which typically occurs at the end of the transport session, session files from the system  600  can be pushed to the server. The information provided to the server can include, for example, the trend, error, blood sample, and event files. Preference can be given to WiFi before cellular link for data transmission, to minimize cost. 
     IX. Possible Benefits 
     Some embodiments of the system  600  described herein can provide one or more benefits. For example: 
     Depending on the type of procedure being performed, manually controlling an organ preservation system can be a labor-intensive process that can require specialized training. Additionally, as with any medical procedure, manual control can also be prone to mistakes by those controlling the system. Thus, in some embodiments, the system  600  can automatically control itself in real time. For example, the controller  150  can be configured to automatically control the flow rate of the pump  106 , the operation of the gas exchanger  114 , the temperature of the heater  110 , the operation of the flow clamp  190  (when an automated clamp is used), and/or the transmission of information to the Cloud. The controller  150  can be configured to control operation of the system  600  based upon feedback information from, for example, the sensors contained therein. 
     Providing automated control of the system  600  can result in improved usability, can reduce the possibility of error, and can reduce the labor intensity of transporting an organ. For example, automating the control process can compensate for user variability that can exist when different people control the system. For example, even if two users receive the same training, one user&#39;s judgment may differ from another which can result in inconsistent levels of care across the two users. By automating the control process, a level of consistency between operators can be achieved in a manner that is otherwise difficult to do. Additionally, providing automated control can also provide better care for the organ while ex vivo by updating operational parameters of the system  600  more quickly than is possible with manual control. 
     The techniques described herein can also improve the utilization of donor organs that are currently not being utilized due to limitations of cold storage methods. In existing cold storage methods, many organs go to waste because the organ cannot be transported to a recipient before it suffers damage as a result of cold storage. This results in many organs that are otherwise suitable for transplantation going to waste each year. Using the techniques described herein, the amount of time that an organ can be maintained in a healthy ex vivo state can be greatly extended thereby increasing the potential donor and recipient pool. 
     The techniques described herein can also help improve the assessment of whether an organ is suitable for transplant into a recipient. For example, using a liver example, visual observation or examination of the liver can be used to assess the liver viability. For instance, a pink or red color of the liver can indicate that the liver is functioning normally, while a gray or dark color of the liver can indicate that the liver is functioning abnormally or deteriorating. In other embodiments, palpation of the liver can be used to assess its viability. When the liver feels soft and elastic, the liver is likely functioning normally. On the other hand, if liver feels tense or stiff, the liver is likely functioning abnormally or deteriorating. 
     In still other embodiments, because the bile duct is cannulated and connected to a reservoir of the system  600 , the color and amount of bile produced by the liver can be easily examined to evaluate the liver viability. In certain embodiments, black or dark green color bile indicates normal liver function while a light or clear color of the bile indicates that the liver is not functioning properly or deteriorating. In still other embodiments, the amount of the bile production can be used to evaluate the liver viability as well. Generally, the more the bile produced, the better the liver function. In certain embodiments, a bile production of from about 250 mL to 1 L, 500 mL to 1 L, 500 mL to 750 mL, 500 mL, 750, or 1 L per day or in any ranges bounded by the values noted herein suggests that the liver preserved on the organ care system  600  is functioning normally and viable. Many of the foregoing techniques can be difficult, if not impossible when the organ is in vivo. 
     X. Examples 
     Experimental tests and results relating to some embodiments are described below. As described below, experimental tests included multiple studies and phases. Phase I included studies of 27 liver samples including two groups of organs on the above OCS system for up to 12 hours. Phase II included replicating the clinical steps of liver retrieval, preservation and simulated transplantation processes for multiple sample livers for 4 hours of simulated transplant. Phase III included replicating clinical steps of liver retrieval, preservation and simulated transplantation processes for multiple sample livers for 24 hours of simulated transplant. 
     A. Phase I 
     Groups A and B of organs were used for Phase I. Objectives for Phase I include: (1) To optimally perfuse and preserve Livers on the OCS system for up to 12 hours using oncotic adjusted red blood cells (“RBCs”) based nutrient enriched perfusate; (2) maintain stable near-physiological heamodynamics (pressure and flow) for both the portal and the hepatic arterial circulation; (3) enable monitoring of organ functionality and stability on the OCS by monitoring bile production rate, liver enzymes trends, stable PH and arterial lactate levels; and (4) histopathology assess the organ post OCS. 
     The animal model used for the test was the swine model, including 70-95 kg Yorkshire swine. The Yorkshire swine was used as a model due to its similarity to human anatomy and size relative to human adult organ size. The perfusate for the test was red blood cell based. Given that the liver is a highly metabolic active organ, a perfusate with an oxygen carrying capacity and nutrient enriched would be ideal for the organ, mimicking it&#39;s in-vivo environment and satisfying the organ&#39;s high metabolic demand. 
     Liver is unique by its dual blood supply. As described previously, the liver gets its blood supply through the portal vein (PV) and the hepatic artery (HA). Portal circulation is a low-pressure circulation (5-10 mm Hg) and the hepatic arterial circulation delivers high-pressure pulsatile blood flow (70-120 mm Hg). Stable perfusion parameters and hemodynamics indicate stable perfusion. Lactate levels were used as a marker of adequate perfusion because lactate is one of the most sensitive physiologic parameters, and is thus a good indicator of the adequacy of perfusion. Lactate is produced under anaerobic conditions denoting inadequate perfusion, and the trend of lactate level is a sensitive marker for perfusion adequacy assessment. Aspartate Aminotransferase (“AST”) is a standard marker used clinically to assess livers, and was also used as a marker of viability. The trend of AST level is another marker and indicator of the organ viability. Bile production is a unique function of the liver. Bile production monitoring is another marker for the organ viability and functionality. 
     Phase I included studies of 27 liver samples. Of those, Group A included 21 samples that were preserved on the OCS for 8-hours using cellular based perfusate. Group B included 6 samples that were preserved on the OCS for 12 hours using cellular based perfusate. 
     The following protocol was applied for phase I groups A and B testing. 
     First, animal prep, organ retrieval, cannulation and Pre-OCS flush is described. Each 70-95 kg Yorkshire Swine was sedated in its cage by injecting a combination of Telazol and Xylazine intramuscularly according to the following dose: 6.6 mg/kg Telazol and 2.2 mg/kg Xylazine. The animal was then intubated, an IV line established, then the animal was transferred to the OR table in supine position, then connected to the ventilator and anesthesia machine. The liver was exposed through a right subcostal incision, and the heart through median sternotomy incision. The hepatic artery (HA), portal vein (PV) and the common bile duct were isolated. The right atrium and the superior vena cave were then isolated and cannulated for blood collection. Then 2-3 liters of blood were collected from the animal using a 40 Fr venous cannula through the right atrium. The collected blood was then processed through a cell saver machine (Haemonetics Cell Saver 5+) to collect washed RBCs. Topical cooling was applied to the liver during the blood collection time. Then the liver was harvested. 
     After harvesting the liver, the hepatic artery (HA), portal vein (PV), the common bile duct, supra hepatic cava and infra hepatic cave were isolated and cannulated using the appropriate size for each. Exemplary sized cannulas include 14 Fr, 16 Fr, 18 Fr for the hepatic artery cannula, 40 Fr and 44 Fr for the portal vein cannula, 12 Fr and 14 Fr for the common bile duct cannula, 40 Fr for the supra-hepatic vena cava, and 40 Fr for the infra-hepatic cava. 
     The liver was then flushed using 3 L of cold PlasmaLyte® solution, each liter was supplemented with Sodium bicarbonate (NHCO3) at 10 mml/L, Epoprostenol Sodium at 2 mics/L, Methylprednisolone at 160 mg/L. One liter was delivered through the hepatic artery pressurized at ˜50-70 mmHg. Two liters were delivered through the portal vein by gravity. 
     After cannulation, the organ was preserved on the OCS at 34° C. for 12 hours using oncotic adjusted RBCs based perfusate. The OCS-liver system prime perfusate included washed red blood cells, albumen 25%, PlasmaLyte® solution, dexamethasone, sodium bicarbonate (NaHCO 3 ) 8.4%, adult multivitamins for infusion (INFUVITE®), calcium gluconate 10% at (100 mg/ml), gram-positive antibiotic such as cefazolin, and a gram negative antibiotic such as ciprofloxacin. Table 7 below summarizes the liver prime perfusate composition and dose. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 OCS liver prime perfusate composition and dose 
               
            
           
           
               
               
            
               
                 OCS Liver Perfusate Composition 
                 Recommended Dose 
               
               
                   
               
            
           
           
               
               
               
            
               
                 Washed Red Blood Cells (pRBCs) 
                 1-2 
                 L 
               
               
                 Albumin 25% 
                 400 
                 mls 
               
               
                 PlasmaLyte ® Solution 
                 700-800 
                 mls 
               
               
                 Methylprednisolone 
                 500 
                 mgs 
               
               
                 Dexamethasone 
                 20 
                 mgs 
               
               
                 Sodium Bicarbonate (NaHCO3) 8.4% 
                 50-70 
                 mmol 
               
               
                 Adult Multivitamins for infusion INFUVITE ® 
                 1 
                 unit 
               
               
                 Calcium Gluconate 10% (100 mg/ml) 
                 10 
                 mls 
               
               
                 Antimicrobials: 
               
               
                 Gram-positive antibiotic: Cefazolin 
                 1 
                 gm 
               
               
                 Gran-negative antibiotic: Ciprofloxacin 
                 100 
                 mg 
               
               
                   
               
            
           
         
       
     
     In addition to OCS-Liver circulating perfusate mentioned above, the following were delivered to the perfusate as continuous infusion using an integrated Alaris infusion pump: Total Parenteral Nutrition (TPN): CLINIMIX E (4.25% Amino Acid/10% Dextrose); PLUS Insulin (30 IU), Glucose (25 g) and 40,000 units of Heparin; Prostacyclin infusion as needed: (epoprostenol sodium) to optimize the Hepatic Artery Pressure; Bile Salts (Taurocholic acid sodium): as needed for Bile Salt Supplement. Table 8 below illustrates the liver perfusate infusions and rate. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 OCS liver perfusate infusions and rate 
               
            
           
           
               
               
            
               
                   
                 Dose 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                 Continuous Infusion Mix 
                   
                   
               
               
                 Total parenteral nutrition (TPN) Mix: 
                 30-50 
                 ml/hr 
               
               
                 CLINIMIX E TPN (4.25% Amino Acid/10% 
               
               
                 Dextrose); PLUS 
               
               
                 Insulin 30 IU 
               
               
                 Glucose 25 gms 
               
               
                 Heparin 40,000 units 
               
               
                 As Needed Additives 
               
               
                 Prostacyclin infusion as needed to control Hepatic 
                 0-6 
                 mics/hr 
               
               
                 artery pressure - e.g. Epoprostenol Sodium 0.5 
               
               
                 mg 
               
               
                 Bile Salts 
                 0-10 
                 ml/hr 
               
               
                 Taurocholic acid sodium (1 gm/50 ml) 
               
            
           
           
               
               
            
               
                 NaHCO3 8.4% to correct metabolic acidosis 
                 1.5 meq/1 bas excess 
               
               
                   
               
            
           
         
       
     
     The Liver was perfused on the OCS by delivering blood based, warm, oxygenated and nutrient enriched perfusate through the hepatic artery and the portal vein. Once the liver was instrumented on the OCS and all cannulae were connected, pump flow was increased gradually and very slowly to achieve the target flow over 10-20 minutes. While the liver was warming up to the temperature set point, the flow control clamp was adjusted to maintain a 1:1 to 1:2 flow ratio between the HA and PV. The vasodilator agent flow rate was adjusted as needed to manage the hepatic artery pressure. An arterial blood sample was collected within the first 15-20 minutes. 
     The following perfusion parameters were maintained during perfusion on the OCS-liver device: Hepatic Artery Pressure (mean HAP): 75-100 mmHg; Hepatic Artery Flow (HAF): 300-700 ml/min; Portal Vein Pressure (mean PVP): 4-8 mmHg; Portal Vein Flow (PVF): 500-900 ml/min; Perfusate Temperature (Temp): 34 C; Oxygen gas flow 400-700 ml/min. 
     Lactate levels on the OCS-Liver Perfusion were collected according to the following sampling scheme. One OCS liver arterial sample was collected within 10-20 minutes from a start of perfusion on the OCS-Liver device. Samples continued to be collected from the device at approximately hourly intervals until lactate level was trending down, at which point the lactate samples were taken every 2 hours or after any active HAF or HAP adjustments. Baseline Liver Enzyme was measured from the animal. Liver Enzyme was collected and assessed on the OCS every two hours starting at the second hour. 
     1. Post OCS Histopathology Sampling. 
     At the end of the preservation time, OCS perfusion was terminated. The liver was disconnected from the device and all cannulas were removed. Specimens were collected from the Liver and saved in 10% formalin for Histopathology assessment. A section of the Liver was collected for the wet/dry ratio. The section weight was recorded before and after 48 hours in an 80° C. hot oven. The wet/dry ration was then calculated according to the following formula: Water Content (W/D ratio)=1−(Ending Weight/Starting Weight). 
     A liver was considered acceptable if it met acceptance criteria, including: stable perfusion parameters throughout preservation on the OCS for HAF, HAP, PVF and PVP; stable or trending down arterial lactate; continuous bile production with a rate of &gt;10 ml/hr.; stable or trending down liver enzymes (AST); and normal and stable perfusate PH. 
     The Phase I, Group A, 21 samples successfully met the above identified acceptance criteria. The data for hepatic artery flow over 8 hours of OCS liver perfusion shown in the graph in  FIG. 31  demonstrates that OCS perfused swine livers demonstrated stable perfusion, as evidenced by the Hepatic Artery Flow (HAF) trend throughout the course of 8 hours preservation on OCS. The data for portal vein flow over 8 hours of OCS liver perfusion shown in the graph in  FIG. 32 , which shows PVF trend throughout the course of the 8-hour preservation on OCS, demonstrated stable perfusion, as evidenced by the stable Portal Vein Flow (PVF) trend throughout the course of 8 hours preservation on OCS.  FIG. 33  shows a graphical depiction of hepatic artery pressure versus portal vein pressure throughout the 8-hour OCS-liver perfusion.  FIG. 33  illustrates that OCS perfused swine livers demonstrated stable perfusion pressure, as evidenced by the stable portal vein pressure and the hepatic artery pressure throughout the course of the 8-hour preservation. 
       FIG. 34  is a graphical depiction of arterial lactate levels over the 8-hour OCS liver perfusion.  FIG. 34  shows that OCS perfused swine livers demonstrated excellent metabolic function, as evidenced by their ability to clear lactate and trending down lactate throughout the course of 8 hours preservation on OCS.  FIG. 35  is a graphical depiction of total bile production over the 8-hour OCS liver perfusion.  FIG. 35  shows that OCS perfused livers continued to produce bile at a rate of &gt;10 ml/hr. throughout the course of the 8-hour preservation on OCS indicating preserved organ functionality.  FIG. 36  is a graphical depiction of AST level over the 8-hour OCS liver perfusion. Aspartate Aminotransferase (AST) is a standard marker clinically used to assess livers.  FIG. 36  graph demonstrates that OCS perfused livers exhibited a trending down AST levels over the course of 8 hours perfusion on the OCS, indicating good liver functionality.  FIG. 37  is a graphical depiction of ACT level over the 8-hour OCS liver perfusion. As shown in  FIG. 37 , activated clotting time (ACT) was maintained above 300 seconds over the course of 8 hours of perfusion on the OCS.  FIG. 38  is a graphical depiction of oncotic pressure throughout the course of 8 hours preservation on OCS. As shown in  FIG. 38 , oncotic pressure remained stable on the OCS. 
       FIG. 39  is a graphical depiction of bicarb levels over the 8-hour OCS liver perfusion. As shown in  FIG. 39 , Bicarb (HCO3) levels were maintained within normal physiologic ranges over the course of 8 hours perfusion on the OCS with very minimal doses required of HCO3 for correction, indicating a stable liver metabolic profile.  FIG. 40  is a depiction of the detected pH levels throughout the course of 8 hours preservation on OCS. As shown in  FIG. 40 , stable and normal pH was maintained over the course of 8 hours perfusion on the OCS with no or minimal need to add HCO3 for correction, indicating a good functioning and adequately perfused organ. 
       FIG. 41  shows images of tissues taken from samples in Phase I, Group A. Histological examination of parenchymal tissue and bile duct tissue shows normal liver sinusoidal structure with no evidence of necrosis or ischemia and normal bile duct epithelial cells indicating adequate perfusion and lack of ischemic injury. 
     The results observed for Phase I Group B, organs maintained for 12 hours, exhibited similar acceptable results to those in Group A. 
     As in Group A above, in Phase I Group B a liver was considered acceptable if it met acceptance criteria, including: stable perfusion parameters throughout preservation on the OCS for HAF, HAP, PVF and PVP; stable or trending down arterial lactate; continuous bile production with a rate of &gt;10 ml/hr.; stable or trending down liver enzymes (AST); and normal and stable perfusate PH. 
       FIG. 42  depicts Hepatic Artery Flow of a 12 hr OCS Liver Perfusion. As illustrated, the graph of  FIG. 42  shows that OCS perfused swine livers demonstrated stable perfusion, as evidenced by the Hepatic Artery Flow (HAF) trend throughout the course of 8 hours preservation on OCS. 
       FIG. 43  depicts Portal Vein Flow of a 12 hr OCS Liver Perfusion. As illustrated, the graph of  FIG. 43  illustrates OCS perfused swine livers demonstrated stable perfusion, as evidenced by the stable Portal Vein Flow (PVF) trend throughout the course of 12 hours preservation on OCS. 
       FIG. 44  depicts Hepatic Artery Pressure vs. Portal Vein Pressure in a 12 hr OCS-Liver Perfusion. The graph of  FIG. 44  demonstrates that OCS perfused swine livers demonstrated stable perfusion pressure, as evidenced by the stable Portal Vein Flow (PVP) and the Hepatic Artery Pressure (HAP) trend throughout the course of 12 hours preservation on OCS. 
       FIG. 45  depicts Arterial Lactate in a 12 hr OCS-Liver Perfusion. The graph of  FIG. 45  shows that OCS perfused swine livers demonstrated excellent metabolic function, as evidenced by their ability to clear lactate and trending down lactate levels throughout the course of 12 hours preservation on OCS. 
       FIG. 46  depicts Bile Production in a 12 hr OCS-Liver Perfusion. The graph of  FIG. 46  demonstrates that the OCS perfused Livers continued to produce bile at a rate of &gt;10 ml/hr throughout the course of 12 hours preservation on OCS indicating well preserved organ function. 
       FIG. 47  depicts AST Level of a 12 hr OCS-Liver Perfusion. Aspartate Aminotransferase (AST) is a standard marker clinically used to assess livers. The graph of  FIG. 47  demonstrates that OCS perfused livers exhibited a trending down AST levels over the course of 12 hours perfusion on the OCS. This indicates good liver functions. 
       FIG. 48  depicts ACT Levels in a 12 hr OCS-Liver Perfusion. Activated clotting time (ACT) was maintained above 300 sec over the course of 12 hours perfusion on the OCS, as illustrated in  FIG. 48 . 
     B. Phase II 
     Phase II, or Group C, included studies of 12 liver samples. Of those, 6 samples were preserved on the OCS for 8 hours using cellular based perfusate and were then subjected to simulated transplant on the OCS for 4 hours of preservation using whole blood as perfusate. The other 6 samples were preserved for 8 hours using cold static preservation in UW solution and were then subjected to simulated transplant on the OCS for 4 hours of preservation using whole blood as perfusate. 
     Objectives for Phase II include preserving the liver with OCS using warm perfusion for 8 hours using an RBCs based perfusate, followed by 45 minutes of cold ischemia, then another 4 hours of OCS-Liver warm perfusion using whole blood, (a) to optimally perfuse and preserve Livers on the OCS system for 8 hours using oncotic adjusted RBCs-based nutrient enriched perfusate, (b) maintain stable near-physiological heamodynamics (pressure and flow) for both the portal and the hepatic arterial circulation, (c) enable monitoring of organ functionality and stability on the OCS by monitoring bile production rate, liver enzymes trends, stable PH and arterial lactate levels, (d) subject the organ to 45 minutes of cold ischemia post the first 8 hours on the OCS, (e) followed by 4 hours of simulated transplant on the OCS using whole blood, while monitoring and assessing the organ heamodynamic and perfusion parameters and monitoring organ functionality. 
     Simulated transplant on the OCS was used to minimize the confounding variables associated with orthotopic transplantation and to isolate the variables to only the ischemia/reperfusion effects. 
     This group (C) of pre-clinical simulated transplant testing was expanded to include a control arm of cold stored swine livers using standard of care cold liver preservation solution. Except for the cold preservation phase, the protocol for this arm of the group was identical to the OCS simulated transplant arm of the same group (C). The detailed protocol and results are described below. 
     Like Phase I, 70-95 kg Yorkshire swine were used as a test subject for Phase II. For this phase, two animals were used for each study, with the first animal as the organ donor, and a second animal as a blood donor for the simulated phase of perfusion on the OCS. 
     In this simulated animal transplant model, the donor organ was exposed to the identical conditions of organ retrieval, preservation, and terminal cooling for transplantation as in orthotopic transplant. The only difference was that in the transplant phase the organ was reperfused with another animal&#39;s un-modified whole blood in an ex-vivo OCS perfusion system to control for all the confounding variables of orthotopic transplants that may shadow the true impact of preservation injury on the donor organ. The donor organ&#39;s function and markers of injury monitored during simulated transplant phase were identical to the ones that would be monitored during orthotopic transplantation. The acceptance criteria for Phase II samples were the same as those outlined above and were measured during the 4 hours of simulated transplant. 
     1. Phase II, Simulated Transplant OCS Arm, 6 Samples (N=6). 
     This set was achieved by replicating all key clinical steps of liver retrieval, preservation and simulated transplantation processes in the following sequence: 
     Donor Organ Retrieval (30-45 minutes): During this phase, the donor organ was retrieved, and cold flushed for 30-45 minutes to replicate the clinical condition of donor liver retrieval and instrumentation on the OCS Liver system. The same prep, organ retrieval, cannulation and pre-OCS flush were performed as described in Phase I. 
     Donor Liver Preservation on OCS (8 hours): During this phase, the donor organ underwent ex-vivo perfusion and assessment using OCS Liver system. During this phase, the liver was monitored and assessed hourly for marker of liver injury (AST level), marker for metabolic function (Lactate level), and bile production rate as a marker for liver function/viability. The same organ preservation was performed for this group as the 8-hour preservation samples described in Phase I. 
     Post-OCS Preservation Cold Ischemia (45 minutes): During this phase the donor liver was flushed using cold flush solution as specified in the proposed clinical protocol to replicate final cooling of the donor liver required for re-implantation. Donor livers were maintained cold for 45 minutes to replicate the time required for performing the re-implantation procedure in the recipient. Using the Final Flush line included in the OCS Liver perfusion termination set, the liver was flushed and cooled on the OCS using 3 L of Cold PlasmaLyte solution supplemented with Sodium bicarbonate (NHCO3) 10 mml/L, Epoprostenol Sodium 2 mcg/L and Methylprednisolone 160 mg/L flush, supplying 1 liter at ˜50-70 mmHg to the hepatic artery, and a 2 liter gravity drain to the portal vein. The liver was then disconnected from the OCS and placed in a cold saline bath for 45 minutes. 
     Final Reperfusion of the Donor Liver (4 hours): The transplantation was replicated/simulated by the following process to isolate the graft assessment markers of ischemia and reperfusion due to preservation technique from other confounding variables associated with the transplant model (described above). The liver graft was reperfused ex-vivo in a new OCS liver perfusion module using normothermic fresh whole blood from a different swine at 37° C. for 4 hours. For the simulated transplant phase, a new perfusion module was used to perfuse the organ on the OCS. The perfusion pressures/flows were controlled to near physiologic levels and temperature was maintained at 37° C. The liver was monitored hourly for the same markers as in the preservation period. In addition, liver tissue samples were evaluated histologically to assess hepatic tissue architecture and any signs of injury in the same way as described above in Phase I. 
     2. Phase II, Simulated Transplant Cold Preservation Control Arm (N=6). 
     This was achieved by replicating all key clinical steps of liver retrieval, preservation and simulated transplantation processes in the following sequence: 
     Donor Organ Retrieval (30-45 minutes): During this phase, the donor organ was retrieved, for 30-45 minutes to replicate the clinical condition of donor liver retrieval. The same prep, organ retrieval, cannulation and pre-OCS flush were performed as described in Phase I. 
     Donor liver cold preservation: During this phase, the donor liver was preserved for 8 hours using standard of care cold storage solution Belzer UW® (UW Solution) for liver flush and storage at 2-5° C. to mimic the standard of care for liver cold preservation. 
     Post-cold Preservation, organ flush and preparation (45 minutes): During this phase the donor liver was flushed with cold flush solution using the final flush line included in the OCS liver perfusion termination set. The liver was flushed using 3 L of cold PlasmaLyte solution supplemented with Sodium bicarbonate (NaHCO3) 10 mml/L, Epoprostenol Sodium 2 mcg/L and Methylprednisolone 160 mg/L flush, supplying 1 liter at ˜50-70 mmHg to the hepatic artery, and a 2 liter gravity drain to the portal vein. The liver was then disconnected from the OCS and placed in a cold saline bath for 45 minutes. 
     Final Reperfusion of the Donor Liver (4 hours): The transplantation was replicated/simulated by the following process to isolate the graft assessment markers of ischemia and reperfusion due to preservation technique from other confounding variables associated with the transplant model (described above). The liver graft was reperfused ex-vivo in a new OCS liver perfusion module using normothermic fresh whole blood from a different swine for 4 hours. The perfusion pressures/flows were controlled to near physiologic levels and temperature was maintained at 37° C. The liver was monitored hourly for the same markers as in the preservation period. In addition, liver tissue samples were evaluated histologically to assess hepatic tissue architecture and any signs of injury in the same way as described above in Phase I. 
     The results observed for Phase II, indicate that samples that were perfused using the OCS system achieved better post-perfusion results than samples that were subjected to cold storage. The samples that were subject to cold storage, did not meet the acceptance criteria described previously during the 4 hours of simulated transplant, as compared to the OCS arm of the group. 
     In the cold storage control arm, the metabolic liver functions demonstrated unstable and worsening profile over the course of the 4 hours of the simulated transplant as evidenced by the higher and unstable lactate trend, as compared to the OCS arm of the group, which demonstrated much better metabolic function, as evidenced by trending down arterial lactate. This indicates that the OCS-arm livers had significantly better metabolic function as compared to the cold storage control arm. In the cold storage control arm, the liver enzyme (AST) profile, which is a sensitive marker of liver injury, was unstable and trending up to much higher levels than the OCS arm of the group. This indicates compromised liver functions for liver grafts in the control arm, as compared to the well persevered and good functioning liver grafts in the OCS arm, which was demonstrated by much lower level of Liver enzyme (AST) trend in the OCS arm. In the cold storage control arm, the pH trend required much higher doses of HCO3 to achieve and maintain a stable metabolic profile, than the doses required for the OCS arm of the group. This indicates that the OCS arm was able to maintain a much better metabolic profile than the cold storage control arm. The bile production rate was less in the cold storage control arm than in the OCS arm. This indicates better liver graft functions in the OCS arm as compared to the cold storage control arm. The perfusion parameters were comparable for both arms of the group. Based on the above comparison results, the OCS arm successfully met the protocol pre-specified acceptance criteria while the cold storage control arm did not meet the identical acceptance criteria. 
       FIG. 49  depicts Hepatic Artery Flow on a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. As illustrated, the graph of  FIG. 49  depicts stable Hepatic Artery Flow (HAF) over the course of 4 hours of perfusion on the OCS during the simulated transplant period. 
       FIG. 50  depicts Portal Vein Flow on a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. As illustrated in  FIG. 50 , the graph demonstrates Stable Portal Vein Flow (PVF) over the course of 4 hours perfusion on the OCS during the simulated transplant period. 
       FIG. 51  depicts Hepatic Artery Pressure vs. Portal Vein Pressure in a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. The graph of  FIG. 51  demonstrates a stable Hepatic Artery Pressure (HAP) and Portal Vein Pressure (PVP) trend over the course of 4 hours perfusion on the OCS. 
       FIG. 52  depicts Arterial Lactate on a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. The graph of  FIG. 52  demonstrate that the OCS-arm perfused livers had a much better metabolic function, as evidenced by trending down arterial Lactate. This indicates that the OCS-arm livers had significantly better metabolic function as compared to cold stored arm. 
       FIG. 53  depicts bile production of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. The graph of  FIG. 53  demonstrates that the OCS arm perfused livers had a higher bile production rate as compared to cold stored livers. This indicates better liver graft function in the OCS group vs. a cold stored group. 
       FIG. 54  depicts a AST Level of simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. The graph of  FIG. 54  demonstrates that the OCS perfused livers had a significantly lower AST levels throughout the 4-hour simulated transplant period. This indicates significantly less liver injury to the graft in the OCS group as compared to the cold stored group. 
       FIG. 55  depicts ACT Levels of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. Activated clotting time (ACT) was maintained above 300 sec over the course of 8 hours perfusion on the OCS. 
       FIG. 56  depicts oncotic pressure of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. As depicted in  FIG. 56 , there was stable oncotic pressure on the OCS-Liver preservation arm. 
       FIG. 57  depicts the Bicarb Level of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. 
       FIG. 58  depicts pH Levels of a simulated transplant OCS-Liver preservation arm vs. a simulated transplant control cold preservation arm. The graph of  FIG. 58  demonstrates that an OCS perfused liver had better pH values over the course of 4 hours of perfusion on the OCS as compared to the cold stored livers. OCS perfused livers needed very minimal HCO3 correction as compared to the cold stored group, this is an indication of better functioning liver grafts in the OCS arm as compared to the control arm. 
     As illustrated in  FIG. 59 , histological examination of Parenchymal tissue and Bile duct tissue shows normal liver sinusoidal structure with no evidence of necrosis or ischemia and normal bile duct epithelial cells indicating adequate perfusion and lack of ischemic injury. 
     As illustrated in  FIG. 60 , histological examination of Parenchymal tissue and Bile duct tissue shows significant hemorrhage and congestion within the parenchyma, Interlobular hemorrhage, multifocal wide spread interlobular hemorrhage, and Lobular congestion. 
     C. Phase III 
     This group of pre-clinical simulated transplant testing was conducted to compare OCS preserved livers (3 samples) for 12 hours versus control arm livers preserved cold (3 samples) using the standard of care cold liver preservation solution Belzer UW® (UW Solution) for 12 hours. Both the OCS arm and the cold storage arm were then assessed for 24 hours in a simulated transplant model on the OCS using leukocyte-reduced blood from a different animal. Except for the cold preservation phase, the protocol for both arms of the group was identical. During the simulated transplant phase, organ function and stability were assessed by monitoring and measuring stable perfusion parameters maintained in pre-specified ranges, bile production, liver biomarkers including AST, ALT, ALP, GGT, and total bilirubin, pH levels, and arterial lactate levels. After the simulated transplant phase, livers were sampled for histopathology assessment. The acceptance criteria for this phase was the same as the acceptance criteria outlined in phase I. 
     1. OCS Arm: 
     Donor Organ Retrieval: During this phase, the donor organ was retrieved, and cold flushed to replicate the clinical condition of donor liver retrieval and instrumentation on the OCS Liver system. The same prep, organ retrieval, cannulation and pre-OCS flush were performed as described in Phase I. 
     Donor Liver Preservation on OCS (12 hours): During this phase, the donor organ underwent ex-vivo perfusion and assessment using OCS Liver system. Similar organ preservation was performed for this group as the 8-hour preservation samples described in phase  1 . The prime perfusate was composed of 1500-2000 ml RBCs (Haemonetics Cell Saver), 400 ml Albumin 25%, 700 ml of PlasmaLyte, Antibiotic (gram positive and gram negative) 1 g Cefazolin and 100 mg Levofloxacin, 500 mg of Solu-Medrol, 20 mg, Dexamethasone, 50 mmol Hco3, 1 vial of multivitamin, and 10 ml of Ca gluconate (4.65 mEq) 
     During preservation, 80% O2 was used starting at a rate of 450 ml/min starting just before organ instrumentation and was adjusted according to the arterial pCO2 and pO2. Temperature was maintained at 34° C. 
     Continuous infusion was delivered using the integrated OCS-SDS. Flolan was added to the HA inflow at 0-20 mic/hr (0-20 ml/hr), as needed (0.05 mg Flolan in 50 ml of Flolan Diluent “1 mic/ml”). CLINIMIX E TPN with 30 IU of insulin, 25 g of glucose and 40000 U of Heparin added was continuously infused to the PV at a rate of 30 mL/h starting with priming. Na Taurocholic Salt, Gama sterilized Bile salt was infused at a rate of 3 mL/h (concentration 1 g/50 ml sterile water) starting with priming. 
     Target pressures and flows were: Portal Vein pressure 1-8 mmHg; Portal Vein flow 0.7-1.7 L/min; Hepatic Artery pressure 85-110 mmHg; and Hepatic artery flow 0.3-0.7 L/min. 
     Using the Final Flush line included in the OCS Liver perfusion termination set, the liver was flushed and cooled on the OCS using 3 L of Cold PlasmaLyte solution, supplying 1 liter at ˜50-70 mmHg to the hepatic artery, and a 2 liter gravity drain to the portal vein. The liver was then disconnected from the OCS and placed in a cold saline bath for 45 minutes. 
     2. Cold Static Preservation Storage Arm: 
     The same prep, organ retrieval, cannulation and pre-OCS flush were performed as described in Phase I. 
     After flushing the organ with 3 Liters of UW, it was stored cold in UW solution at temperature ˜5 degree for 12 hours. Using the Final Flush line included in the OCS Liver perfusion termination set, the liver was flushed and cooled on the OCS using 3 L of Cold PlasmaLyte solution, supplying 1 liter at ˜50-70 mmHg to the hepatic artery, and a 2-liter gravity drain to the portal vein. The liver was then disconnected from the OCS and placed in a cold saline bath for 45 minutes. 
     Both sets of livers were subjected to the post-transplant phase for 24 hours, where they were instrumented onto an OCS machine and supplied with a post-perfusate solution comprising 1500-3000 ml leukocytes reduced blood, 100 ml Albumin 25%, Antibiotic (gram positive and gram negative) 1 g Cefazolin and 100 mg Levofloxacin, 500 mg of Solu-Medrol, 20 mg, Dexamethasone, 50 mmol HCO3, 1 vial of multivitamin, and 10 ml of Ca gluconate (4.65 mEq). During simulated transplant, 80% O2 was used starting at a rate of 450 ml/min starting just before organ instrumentation and was adjusted according to the arterial pCO2 and pO2. Temperature was maintained at 37° C. 
     Continuous infusion was delivered using the integrated OCS-SDS. Flolan was added to the HA inflow at 0-20 mic/hr. (0-20 ml/hr.), as needed (0.05 mg Flolan in 50 ml of Flolan Diluent “1 mic/ml”). CLINIMIX E TPN with 30 IU of insulin, 25 g of glucose and 40000 U of Heparin added was continuously infused to the PV at a rate of 30 mL/h starting with priming. Na Taurocholic Salt, Gama sterilized Bile salt was infused at a rate of 3 mL/h (concentration 1 g/50 ml sterile water) starting with priming. 
     Target pressures and flows were: Portal Vein pressure 1-8 mmHg; Portal Vein flow 0.7-1.7 L/min; Hepatic Artery pressure 85-110 mmHg; and Hepatic artery flow 0.3-0.7 L/min. 
     Using the Final Flush line included in the OCS Liver perfusion termination set, the liver was flushed and cooled on the OCS using 3 L of Cold PlasmaLyte solution, supplying 1 liter at ˜50-70 mmHg to the hepatic artery, and a 2 liter gravity drain to the portal vein. Each Liter will be supplemented by 10 mmol HCO3 and 150 mg of Solu-Medrol. The liver was then disconnected from the OCS and placed in a cold saline bath for 45 minutes. Table 9 below illustrates the liver perfusate infusions and rate. 
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 OCS liver perfusate infusions and rate 
               
            
           
           
               
               
            
               
                   
                 Dose 
               
               
                   
                   
               
            
           
           
               
               
               
            
               
                 Continuous Infusion Mix 
                   
                   
               
               
                 Total parenteral nutrition (TPN) Mix: 
                 30 
                 ml/hr 
               
               
                 CLINIMIX E TPN (4.25% Amino Acid/10% 
               
               
                 Dextrose); PLUS 
               
               
                 Insulin 30 IU 
               
               
                 Glucose 20 gms 
               
               
                 Heparin 40,000 units 
               
               
                 As Needed Additives 
               
               
                 Prostacyclin infusion as needed to control Hepatic 
                 0-20 
                 mics/hr 
               
               
                 artery pressure - e.g. Epoprostenol Sodium 0.5 
               
               
                 mg 
               
               
                 Bile Salts 
                 0-10 
                 ml/hr 
               
               
                 e.g. Taurocholic acid sodium (1 gm/50 ml) 
               
            
           
           
               
               
            
               
                 NaHCO3 8.4% to correct metabolic acidosis 
                 1.5 mEq/1 base excess 
               
               
                   
               
            
           
         
       
     
       FIG. 61  is a samples location diagram illustrating locations of samples from a liver of a pig. 
     The following liver histopathology sampling protocol was followed to assess the sample livers. 
     Samples collection time: At completion of the experiment (at the end of the 24 hr simulated transplant phase). 
     Method and Samples Collected: 
     1. Gross Picture: photographs of capsular and under surface of the OCS and CS livers at the beginning of the gross examination post study.
 
2. Bile Duct: entire extra-hepatic bile duct and as much adherent surrounding tissue (not surgically dissected from the surrounding tissue) in a neutral-buffered formalin jar.
 
3. Electron Microscopy (EM): 0.1 cm (1 mm) fragment of the liver tissue from the peripheral and deep aspect of the Left Lateral Lobe and the Right Medial Lobe. Place the tissue specimen in electron microscopy fixative.
 
4. Hepatic Parenchyma (LM): 1×1 cm sections obtained from the periphery and deep aspects of each lobe (total of 8), and preserved in Formalin. Sections thickness no more than 3-5 mm and fixative volume 15-20 times higher than the specimen volume. Any obvious defect was sampled.
 
     Samples Locations: 
     Two samples were collected from each lobe according to the  FIG. 61  to access the hepatic parenchyma, each sample will be preserved in separate jar filled with 10% formalin and labeled accordingly. 
     1.  eft  ateral  obe  eripheral-  ( )
 
2.  eft  ateral  obe  eripheral-  ( )
 
3.  eft  ateral  obe  eep-  ( )
 
4.  eft  ateral  obe  eep-  ( )
 
5.  eft  edial  obe  eripheral-  ( )
 
6.  eft  edial  obe  eep-  ( )
 
7.  ight  edial  obe  eripheral-  ( )
 
8.  ight  edial  obe  eripheral-  ( )
 
9.  ight  edial  obe  eep-  ( )
 
10.  ight  edial  obe  eep-  ( )
 
11.  ight  ateral  obe  eripheral-  ( )
 
12.  ight  ateral  obe  eep-  ( )
 
13.  xtra- epatic  ile  uct ( )
 
     Data Collection and Analysis 
     Preservation data was summarized in tabular and graphic form, depending on the variable. Then continuous variables were analyzed with means, medians, standard deviations, and minimum and maximum values. After that, AST, ALT, GGT, ALP test results were collected, recorded and attached. Next, arterial lactate was collected, recorded and attached. pH was then measured, recorded and attached. HCO3 levels were then measured, recorded and attached. Lastly, total bile produced volume was collected and recorded. 
     Results of Phase III. 
     The OCS arm (N=3) of this group successfully met all of the acceptance criteria, which was pre-specified in the protocol, by demonstrating the following throughout the 24 hours of the simulated transplant phase: Stable perfusion parameters throughout preservation on the OCS for HAF, HAP, PVF and PVP, stable or trending down arterial lactate, continuous bile production with a rate of &gt;10 ml/hr., stable or trending down liver enzymes (AST), and normal and stable perfusate PH. For example,  FIG. 62  illustrates the Hepatic Artery Pressure (HAP) trend over the course of 24 hours perfusion on the OCS. 
       FIG. 63  illustrates the Portal Vein Pressure in an OCS-Liver Preservation arm vs the control Cold preservation arm.  FIG. 63  demonstrates the Portal Vein Pressure (PVP) trend over the course of 24 hours perfusion on the OCS; the cold preservation arm demonstrated an increase in the PVP over time compared to stable PVP for the OCS preservation arm. 
       FIG. 64  illustrates a Hepatic Artery Flow in a OCS-Liver Preservation arm vs. control Cold preservation arm.  FIG. 64  demonstrates stable Hepatic Artery Flow (HAF) trend over the course of 24 hours perfusion on the OCS. 
       FIG. 65  illustrates a Portal Vein Flow in an OCS-Liver Preservation arm vs. control Cold preservation arm.  FIG. 65  demonstrates stable Portal Vein Flow (PVF) trend over the course of 24 hours perfusion on the OCS. 
     In comparison, the simulated transplant OCS arm (N=3) performed better than the control arm. The perfusion parameters were comparable for both arms of the group however the control arm vascular resistance was higher compared to the OCS arm. The control arm had a much higher peak of the Lactate level at 7.8 mmol/L compared to 2.4 mmol/L for the OCS arm. Both arms continued to produce bile throughout the simulated transplant phase at a rate&gt;10 ml/hr. For example,  FIG. 66  depicts Arterial Lactate in an OCS-Liver Preservation arm vs. a control Cold preservation arm.  FIG. 66  demonstrates Arterial Lactate in an OCS-Liver Preservation arm vs. control Cold preservation arm. This indicates that the OCS-arm livers had significantly better metabolic function as compared to cold stored arm. 
     Liver enzymes which is a sensitive biomarker of Liver injury (AST, ALT, and the GGT) showed a much higher peaks compared to the OCS arm of the group. Average AST peak was 88.7 in the OCS arm compared to  1188  for the control arm. Average ALT levels peaked at 31.3 for the OCS arm compared to a peak of 82 for the control arm. Average GGT levels peaked at 28.7 for the OCS arm compared to 97 for the control arm. This indicates well preserved Livers and less cell injury for Liver grafts preserved on the OCS arm as compared to the control arm. For example,  FIG. 67  illustrates an AST Level OCS-Liver Preservation arm vs. control Cold Preservation arm.  FIG. 67  demonstrates that the OCS perfused livers had significantly lower AST levels throughout the 24 hours simulated transplant period. This indicates significantly less liver injury to the graft in the OCS group as compared to the cold stored group. 
       FIG. 68  illustrates an ALT Level OCS-Liver Preservation arm vs. control Cold preservation arm.  FIG. 68  demonstrates that the OCS perfused livers had lower ALT levels with an average peak at 31.3 compared to average peak of 82 for the control group. This indicates less liver injury to the graft in the OCS arm as compared to the control cold stored arm. 
       FIG. 69  depicts a GGT Level of an OCS-Liver Preservation arm vs. control Cold preservation arm.  FIG. 69  demonstrates that the OCS perfused livers had a much lower GGT levels throughout the 24 hr. period. This indicates better hepatobilliary protection of the graft in the OCS arm as compared to the control cold stored arm. 
     The OCS arm demonstrated better metabolic profile compared to the control arm as manifested by the stable and normal pH levels compared to a lower pH for the control arm. This indicates that the OCS arm was able to maintain a much better metabolic profile than the control arm. For example,  FIG. 70  depicts a pH level of an OCS-Liver Preservation arm vs. a control Cold preservation arm. As demonstrated by  FIG. 70 , OCS perfused livers had normal and stable pH values over the course of 24 hours of perfusion as compared to the Control cold preservation arm livers. 
     Also the OCS arm demonstrated better metabolic Liver functions as shown by higher HCO3 levels over the course of the 24 hours of the simulated transplant, as compared to the control arm of the group, which demonstrated lower HCO3 throughout the simulated transplant phase. This indicates that the OCS-arm livers had better metabolic function as compared to the control arm. For example,  FIG. 71  depicts a HCO3 level in an OCS-Liver Preservation arm vs. a Control Cold preservation arm. As illustrated in  FIG. 71 , OCS perfused livers had higher HCO3 levels over the course of 24 hours of perfusion as compared to the Control cold preservation arm livers. 
       FIG. 72  depicts a bile production OCS-Liver Preservation arm vs. control Cold preservation arm.  FIG. 72  demonstrates that both arms maintained bile production rate of &gt;10 ml/hr. Based on the above presented data, The OCS has demonstrated stable perfusion and metabolic profile with well-preserved liver graft functions for up to 12 hours of OCS preservation. In addition, when compared to the control arm of cold static preservation, in the simulated transplant model, the OCS perfused swine livers demonstrated a significantly better metabolic function, as evidenced by their ability to metabolize lactate to baseline levels as compared to cold stored livers where lactate continued to rise to significantly higher levels. Additionally, the OCS perfused swine livers had significantly lower AST levels as compared to the much higher level of AST in the simulated transplant control arm, which indicates better Liver graft functions in the OCS arm as compared to the control cold stored arm. The results of this pre-clinical OCS Liver device testing demonstrated that the OCS device is safe and effective in preservation of swine livers, as evidenced by meeting the specified acceptance criteria. The differences observed between the control arm and the OCS arm in Phase III were similar to the differences observed in Phase II, indicating that the OCS arm had better results. Additional uses 
     While preservation of a donor organ which is intended for transplantation has been described above, some embodiments of the organ care system  600  described herein can be used for other purposes. For example, the system  600  can also be used for maintaining an organ during reconstructive or other types of surgery, therapy, and/or treatment (e.g., complicated, high-risk surgeries and/or treatments). That is, some surgeries, therapies, and/or treatments can be damaging to the human body, if the procedure were performed on an in vivo organ. Thus, it can be beneficial to remove the organ from the patient&#39;s body, perform surgery on and/or treat the organ ex vivo, and then reimplant the organ back into the patient&#39;s body. For example, certain radiation therapies can be damaging to tissue surrounding the organ. Thus, by removing the organ, intensive radiation therapy can be performed on the organ without collateral damage to the patient&#39;s body. Other embodiments are possible. 
     D. Ex-Vivo Treatment of Diseased Livers, Including Cancer, Fatty Livers, Infection, by Delivery of Therapeutics to Organ 
     In some embodiments, the liver preserved on the organ care system  600  can be subjected to ex-vivo therapeutic treatment of liver diseases. Non-limiting examples of liver diseases include cancer, fatty livers, and liver infection. The therapy can be conducted by adding therapeutic agents to the perfusion fluid circulating through the organ care system  600 , thereby providing it to the liver itself. Alternatively, the therapeutic agents can be directly added into one or more nutritional solution described herein. In some embodiments, the temperature of the perfusion fluid and/or liver can be maintained at 40° C. or 42° C., which can accelerate the rate of breakdown and dissolution of fatty cells in the liver. 
     Non-limiting examples of anti-cancer therapeutic agents suitable for ex-vivo therapeutic treatment of liver cancer include microtubule binding agents, DNA intercalators or cross-linkers, DNA synthesis inhibitors, DNA and/or RNA transcription inhibitors, antibodies, enzymes, enzyme inhibitors, gene regulators, and/or angiogenesis inhibitors. Anti-cancer “Microtubule binding agent” refers to an agent that interacts with tubulin to stabilize or destabilize microtubule formation thereby inhibiting cell division. Examples of microtubule binding agents include, without limitation, paclitaxel, docetaxel, vinblastine, vindesine, vinorelbine (navelbine), the epothilones, colchicine, dolastatin 15, nocodazole, podophyllotoxin and rhizoxin. Analogs and derivatives of such compounds also can be used and will be known to those of ordinary skill in the art. 
     Anti-cancer DNA and/or RNA transcription regulators include, without limitation, actinomycin D, daunorubicin, doxorubicin and derivatives and analogs thereof. DNA intercalators and cross-linking agents include, without limitation, cisplatin, carboplatin, oxaliplatin, mitomycins, such as mitomycin C, bleomycin, chlorambucil, cyclophosphamide and derivatives and analogs thereof. DNA synthesis inhibitors include, without limitation, methotrexate, 5-fluoro-5′-deoxyuridine, 5-fluorouracil and analogs thereof. Examples of suitable enzyme inhibitors include, without limitation, camptothecin, etoposide, formestane, trichostatin and derivatives and analogs thereof. Other anti-tumor agents can include adriamycin, apigenin, rapamycin, zebularine, cimetidine, and derivatives and analogs thereof. Any other suitable liver cancer therapeutic agents known in the art are contemplated. 
     A further advantage of the chemotherapy described above is its specificity: the anticancer agent is specifically delivered to the diseased organ, the liver, without any undesirable toxicity to other healthy organs or tissues. 
     Non-limiting examples of therapeutic agents suitable for ex vivo therapeutic treatment of fatty liver disease include pioglitazone, rosiglitazone, orlistat, ursodiol, and betaine. Any other suitable fatty liver therapeutic agents known in the art are contemplated. 
     Non-limiting examples of therapeutic agents suitable for ex-vivo therapeutic treatment of liver infection include terferon alfa-2b, terferon alfa-2a, ribavirin, telaprevir, boceprevir, simeprevir, and sofobuvir. Any other suitable liver infection therapeutic agents known in the art are contemplated. 
     E. Regenerative Approaches Including Stem Cell or Gene Delivery 
     In other embodiments, the organ preserved by the organ care system  600  described herein can be subjected to regenerative treatments. Non-limiting examples of the organ regenerative treatments include stem cell therapy or gene delivery therapy. Stem cells are undifferentiated biological cells that can differentiate into specialized cells, e.g., hepatocytes. Adult stem cells can be harvested from blood, adipose, and bone marrow of the donor of the liver with various types of liver diseases, or of another adult with compatible stem cells (stem cells transplantation). The isolated stem cells, e.g., bone marrow cells, can be used to infuse the damaged or diseased liver preserved on the organ care system  600  to repair the liver to a healthier state. For instance, the isolated stem cells can be isolated from the donor and included in the blood product in the perfusion fluid. 
     In some other embodiments, the liver preserved by the organ care system  600  described herein can be subjected to gene delivery therapy. Gene delivery is the process of introducing foreign DNA into host cells, e.g., liver cells, to effect treatment of diseases. In certain embodiments, the gene delivery therapy is virus-mediated gene delivery utilizing a virus to inject its DNA inside the liver cells. Non-limiting examples of suitable viruses include retrovirus, adenovirus, adeno-associated virus and herpes simplex virus. In some embodiments, a gene that is used to treat certain liver diseases is packaged into a vector (virus or other) and included as part of the perfusion fluid to perfuse the liver or added to the circulation of the organ care system  600  directly. 
     F. Ex-Vivo Immune Modulation 
     In other embodiments, the donor&#39;s liver preserved by the organ care system  600  described herein can be subjected to immune regulations. Immune responses and their modulation within the liver can affect the outcome liver transplantation. More importantly, a liver disease can be treated by inducing, enhancing, or suppressing an immune response from the liver. For instance, the liver immune system can be activated to attack malicious tissues to treat liver cancer. On the other hand, the liver immune system can be suppressed to treat autoimmune liver disease such as autoimmune hepatitis. Any immunosuppressive agents or immune activating agents known in the art can be used to treat the preserved liver to achieve the desirable effect. 
     G. Ex-Vivo Surgical Treatment of Livers 
     In yet other embodiments, the donor&#39;s liver preserved by the organ care system  600  described herein can be subjected to surgical treatment such as liver tumor resection or split transplant where the liver is divided between two recipient patients. In yet other embodiments, the donor&#39;s liver preserved by the organ care system  600  described herein can be subjected to irradiation therapy to treat certain liver diseases such as liver cancer. 
     XI. Conclusion 
     Other embodiments are within the scope and spirit of the disclosed subject matter. In some embodiments, a perfusion circuit for perfusing a liver ex-vivo is disclosed, which comprises a pump for providing pulsatile fluid flow of a perfusion fluid through the circuit, a gas exchanger, a divider in fluid communication with the pump configured to divide the perfusion fluid flow into a first branch and a second branch wherein the first branch comprises a hepatic artery interface wherein the first branch is configured to provide a first portion of the perfusion fluid to a hepatic artery of the liver at a high pressure and low flow rate via the hepatic artery interface wherein the first branch is in fluid pressure communication with the pump wherein the second branch comprises a portal vein interface wherein the second branch is configured to provide a second portion of the perfusion fluid to a portal vein of the liver at a low pressure and high flow rate via the portal vein interface the second branch further comprising a clamp located between the divider and the portal vein interface for selectively controlling the flow rate of perfusion fluid to the portal vein the second branch further comprising a compliance chamber configured to reduce the pulsatile flow characteristics of the perfusion fluid from the pump to the portal vein wherein the pump is configured to communicate fluid pressure through the first and second branches to the liver, a drain configured to receive perfusion fluid from an uncannulated inferior vena cava of the liver, and a reservoir positioned below the liver and located between drain and the pump, configured to receive the perfusion fluid from the drain and store a volume of fluid. 
     In certain embodiments, the second branch of a perfusion circuit comprises a plurality of compliance chambers. In certain embodiments, a compliance chamber in a perfusion circuit is located between the divider and the portal vein interface. In certain embodiments, a portal vein interface of a perfusion circuit has a larger cross sectional area than a hepatic artery interface. In certain embodiments, a perfusion circuit includes at least one flow rate sensor in a second branch, and at least one pressure sensor. In certain embodiments, a pump comprises a pump driver, and the position of the pump driver is adjustable to control the pattern of pulsatile flow to a liver. In some embodiments a clamp comprises an engaged position and a disengaged position, the clamp may be adjusted to select the desired clamping force and corresponding flow rate when the clamp is in the disengaged position, the clamp may be moved to the engaged position to apply the selected clamping force without further adjustment when in the engaged position, such that a user may quickly engage and disengage the clamp while still having precise control over the amount of clamping force applied to the perfusion circuit. 
     In some embodiments, a system for perfusing an ex vivo liver at near physiologic conditions is disclosed, the system comprising a perfusion circuit comprising a pump for pumping perfusion fluid through the circuit, the pump in fluid communication with a hepatic artery interface and a portal vein interface, wherein the pump provides perfusion fluid to a hepatic artery of the liver at a high pressure and low flow rate via the hepatic artery interface; and wherein the pump provides perfusion fluid to the a portal vein of the liver at a low pressure and high flow rate via the portal vein interface, a gas exchanger, a heating subsystem for maintaining the temperature of the perfusion fluid at a normothermic temperature, a drain configured to receive the perfusion fluid from an inferior vena cava of the liver, a reservoir configured to receive perfusion fluid from the drain and store a volume of fluid. In some embodiments, a heating subsystem is configured to maintain the perfusion fluid at a temperature between 34-37° C. In some embodiments, the perfusion circuit comprises an inferior vena cava cannula. In some embodiments, a control system for controlling operation of the system is disclosed, comprising an onboard computer system connected to one or more of the components in the system, a data acquisition subsystem comprising at least one sensor for obtaining data relating to the organ, and a data management subsystem for storing and maintaining data relating to operation of the system and with respect to the liver. In some embodiments, a heading subsystem comprises a dual feedback loop for controlling the temperature of the perfusion fluid within the system. 
     In some embodiments, a system for preserving a liver ex vivo at physiologic conditions is disclosed, comprising a multiple use module comprising a pulsatile pump, a single use module comprising, a perfusion circuit configured to provide perfusion fluid to the liver, a pump interface assembly for translating pulsatile pumping from the pump to the perfusion fluid, a hepatic artery interface configured to deliver perfusion fluid to a hepatic artery of the liver, a portal vein interface configured to deliver perfusion fluid to a portal vein of the liver, a divider to supply perfusion fluid flow from the pump interface assembly to the hepatic artery interface at a high pressure and low flow rate and to the portal vein interface at a low pressure and high flow rate, an organ chamber assembly configured to hold an ex vivo organ, the organ chamber assembly including a housing, a flexible support surface suspended within the organ chamber assembly, and a bile container configured to collect bile produced by the liver. 
     In some embodiments, flexible support surface is configured to conform to differently sized organs, and further comprising projections to stabilize the liver in the organ chamber assembly. In some embodiments, a flexible support surface comprises a top layer, a bottom layer, and a deformable metal substrate positioned between the top layer and the bottom layer. In some embodiments, a flexible support surface is configured to cradle and controllably support a liver without applying undue pressure to the liver. In some embodiments, a single use module comprises a wrap configured to cover the liver in the organ chamber assembly. In some embodiments, a single use module comprises a sensor to measure the volume of bile collected in the bile container. In some embodiments, a single use module can be sized and shaped for interlocking with a portable chassis of the multiple use module for electrical, mechanical, gas and fluid interoperation with the multiple use module. In some embodiments, multiple and single use modules can communicate with each other via an optical interface, which comes into optical alignment automatically upon the single use disposable module being installed into the portable multiple use module. 
     The subject matter described herein can be implemented using digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed in this specification and structural equivalents thereof, or in combinations of them. The subject matter described herein can be implemented as one or more computer program products, such as one or more computer programs tangibly embodied in an information carrier (e.g., in a machine-readable storage device), or embodied in a propagated signal, for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). A computer program (also known as a program, software, software application, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file. A program can be stored in a portion of a file that holds other programs or data, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. 
     The processes and logic flows described in this specification, including the method steps of the subject matter described herein, can be performed by one or more programmable processors executing one or more computer programs to perform functions of the subject matter described herein by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus of the subject matter described herein can be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). 
     Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processor of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random-access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks, (e.g., internal hard disks or removable disks); magneto-optical disks; and optical disks (e.g., CD and DVD disks). The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry. 
     To provide for interaction with a user, the subject matter described herein can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, (e.g., a mouse or a trackball), by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well. For example, feedback provided to the user can be any form of sensory feedback, (e.g., visual feedback, auditory feedback, or tactile feedback), and input from the user can be received in any form, including acoustic, speech, or tactile input. 
     The techniques described herein can be implemented using one or more modules. As used herein, the term “module” refers to computing software, firmware, hardware, and/or various combinations thereof. At a minimum, however, modules are not to be interpreted as software that is not implemented on hardware, firmware, or recorded on a non-transitory processor readable recordable storage medium (e.g., modules are not software per se). Indeed “module” is to be interpreted to always include at least some physical, non-transitory hardware such as a part of a processor or computer. Two different modules can share the same physical hardware (e.g., two different modules can use the same processor and network interface). The modules described herein can be combined, integrated, separated, and/or duplicated to support various applications. Also, a function described herein as being performed at a particular module can be performed at one or more other modules and/or by one or more other devices instead of or in addition to the function performed at the particular module. Further, the modules can be implemented across multiple devices and/or other components local or remote to one another. Additionally, the modules can be moved from one device and added to another device, and/or can be included in both devices. 
     The subject matter described herein can be implemented in a computing system that includes a back-end component (e.g., a data server), a middleware component (e.g., an application server), or a front-end component (e.g., a client computer having a graphical user interface or a web browser through which a user can interact with an implementation of the subject matter described herein), or any combination of such back-end, middleware, and front-end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet.