Patent Publication Number: US-2020282116-A1

Title: Collection, Genome Editing, And Washing Of T-Cell Lymphocytes

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority of U.S. Provisional Patent Application Ser. No. 62/814,050, filed Mar. 5, 2019, the contents of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates to collection of mononuclear cells (“MNCs”) and T-cell lymphocytes. More particularly, the present disclosure relates to the collection, genome editing, and washing of T-cell lymphocytes. 
     Description of Related Art 
     Various blood processing systems now make it possible to collect particular blood constituents, rather than whole blood, from a blood source. Typically, in such systems, whole blood is drawn from a source, the particular blood component or constituent is removed and collected, and the remaining blood constituents are returned to the source. 
     Whole blood is typically separated into its constituents through centrifugation. This requires that the whole blood be passed through a centrifuge after it is withdrawn from, and before it is returned to, the source. To avoid contamination and possible infection of the source, the blood is preferably contained within a sealed, sterile fluid flow system during the entire centrifugation process. Typical blood processing systems thus include a permanent, reusable centrifuge assembly containing the hardware (drive system, pumps, valve actuators, programmable controller, and the like) that spins and pumps the blood, and a disposable, sealed and sterile fluid processing assembly that is mounted in cooperation on the hardware. The centrifuge assembly engages and spins a disposable centrifuge chamber of the fluid processing assembly during a collection procedure. The blood, however, makes actual contact only with the fluid processing assembly, which assembly is used only once and then discarded. 
     As the whole blood is spun by the centrifuge, the heavier (greater specific gravity) components, such as red blood cells, move radially outwardly away from the center of rotation toward the outer or “high-G” wall of the separation chamber. The lighter (lower specific gravity) components, such as plasma, migrate toward the inner or “low-G” wall of the separation chamber. Various ones of these components can be selectively removed from the whole blood by forming appropriately located channeling seals and outlet ports in the separation chamber. 
     An exemplary method of centrifugally separating and collecting MNCs including T-cell lymphocytes) is described in U.S. Pat. No. 5,980,760, which is incorporated herein by reference. In such a procedure, whole blood in a centrifuge is separated into platelet-poor plasma, an interface or MNC-containing layer, and packed red blood cells. The platelet-poor plasma is collected for later use, while the packed red blood cells are returned to the blood source and the MNC-containing layer remains in the centrifuge. When a target amount of platelet-poor plasma has been collected, an MNC accumulation phase begins. During this phase, the position of the interface within the centrifuge is moved closer to the low-G wall, such that platelet-rich plasma and packed red blood cells are removed from the centrifuge while the MNC-containing layer continues to build up in the centrifuge. Portions of the platelet-rich plasma and the packed red blood cells are returned to the blood source, with the remainder of the platelet-rich plasma and packed red blood cells being recirculated through the centrifuge to maintain a proper hematocrit. 
     When a certain amount of blood has been processed, the return and recirculation of the packed red blood cells is ended and a red blood cell collection phase begins. During this phase, recirculation and return of the platelet-rich plasma continues, while the packed red blood cells are conveyed from the centrifuge via an outlet port to a red blood cell collection container for later use. 
     When a target amount of packed red blood cells has been collected, an MNC harvest phase begins. To harvest the MNCs in the MNC-containing layer, the packed red blood cells are temporarily prevented from exiting the centrifuge. At least a portion of the collected red blood cells is conveyed into the centrifuge via the same inlet port by which whole blood had previously been flowing into the centrifuge, which forces the MNC-containing layer to exit the centrifuge via the same outlet as the platelet-rich plasma. The platelet-rich plasma exiting the centrifuge ahead of the MNC-containing layer is directed into the platelet-poor plasma container, with the MNC-containing layer subsequently being directed into an MNC collection container. 
     Following the MNC harvest phase, a plasma flush phase begins. During this phase, plasma from the platelet-poor plasma container is used to flush any MNC-containing layer positioned between the separation chamber and the MNC collection container back into the separation chamber. The MNC-containing layer flushed back into the separation chamber may be subsequently collected by repeating the various phases, until a target amount of MNC product has been collected. 
     Following collection, the MNC product may be treated to further processing, including electroporation-based treatment, such as chimeric antigen receptor (“CAR”) T-cell therapy. CAR T-cell therapy includes employing electroporation to open the pores of a cell membrane, which allows DNA to enter and modify the genome of a T-cell, such as in a way that will help aid the cell in targeting cancer cells when reinfused into a patient. Typically, the MNC product is subjected to CAR T-cell therapy at a different location than the location in which the MNC product is collected, which requires disconnection of the patient from the apheresis device and subsequent reconnection of the patient for reinfusion (if the blood source is the same patient receiving the genetically modified T-cells), with a possibly significant delay between blood draw and reinfusion. Transporting the MNC product between the locations may also be expensive. 
     SUMMARY 
     There are several aspects of the present subject matter which may be embodied separately or together in the devices and systems described and claimed below. These aspects may be employed alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to preclude the use of these aspects separately or the claiming of such aspects separately or in different combinations as set forth in the claims appended hereto. 
     In one aspect, a fluid processing system includes a separation device, an electroporation device, a pump assembly including a plurality of pumps, and a controller. The controller is configured to actuate the pump assembly to convey blood from a blood source into the separation device, actuate the separation device to separate a mononuclear cell product from the blood, actuate the pump assembly to convey at least a portion of the mononuclear cell product into the electroporation device to modify a genome of at least one of the cells of the mononuclear cell product, and actuate the pump assembly to convey at least a portion of the modified mononuclear cell product to the blood source. 
     In another aspect, a method is provided for processing blood. The method includes drawing blood from a blood source into a fluid flow circuit and separating a mononuclear cell product from the blood. At least a portion of the mononuclear cell product is conveyed into an electroporation device without disconnecting the blood source from the fluid flow circuit to modify a genome of at least one of the cells of the mononuclear cell product. At least a portion of the modified mononuclear cell product is returned to the blood source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary blood separation device that comprises a component of a blood separation system according to an aspect of the present disclosure; 
         FIG. 2  is a schematic view of an exemplary disposable fluid flow circuit that may be mounted to the blood separation device of  FIG. 1  to complete a blood separation system according to an aspect of the present disclosure; 
         FIG. 3  is a perspective view of an exemplary centrifugal separator of the blood separation device of  FIG. 1 , with the centrifugal separation chamber of a fluid flow circuit mounted therein; 
         FIG. 4  is a top plan view of an exemplary cassette of a fluid flow circuit, which can be actuated to perform a variety of different blood processing procedures in association with the blood separation device shown in  FIG. 1 ; 
         FIG. 5  is a perspective view of the centrifugal separator of  FIG. 3 , with selected portions thereof broken away to show a light source of an interface monitoring system; 
         FIG. 6  is a perspective view of the centrifugal separator of  FIG. 3 , with the light source operating to transmit a light beam to a light detector of the interface monitoring system; 
         FIG. 7  is a perspective view of the centrifugal separator of  FIG. 3 , with selected portions thereof broken away to show the light source and light detector of the interface monitoring system; 
         FIG. 8  is a perspective view of an exemplary spinning membrane separator of a fluid flow circuit; 
         FIG. 9  is a perspective view of the spinning membrane separator of  FIG. 8  and a portion of a spinning membrane separator drive unit, with portions of both being cut away for illustrative purposes; 
         FIG. 10  is a perspective view of an exemplary centrifugal separation chamber of a fluid flow circuit; 
         FIG. 11  is a front elevational view of the centrifugal separation chamber of  FIG. 10 ; 
         FIG. 12  is a bottom perspective view of the fluid flow path through the centrifugal separation chamber of  FIG. 10 ; 
         FIG. 13  is a perspective view of another embodiment of a centrifugal separation chamber of a fluid flow circuit; 
         FIG. 14  is a front elevational view of the centrifugal separation chamber of  FIG. 13 ; 
         FIG. 15  is a top perspective view of the fluid flow path through the centrifugal separation chamber of  FIG. 13 ; 
         FIG. 16  is a perspective view of a third embodiment of a centrifugal separation chamber of a fluid flow circuit; 
         FIG. 17  is a front elevational view of the centrifugal separation chamber of  FIG. 16 ; 
         FIG. 18  is an enlarged perspective view of a portion of a channel of any of the centrifugal separation chambers of  FIGS. 10-17 , with an interface between separated blood components being positioned at a (typically) desired location on a ramp defined within the channel; 
         FIG. 19  is an enlarged perspective view of the channel and ramp of  FIG. 18 , with the interface being at a (typically) undesired high location on the ramp; 
         FIG. 20  is an enlarged perspective view of the channel and ramp of  FIG. 18 , with the interface being at a (typically) undesired low location on the ramp; 
         FIG. 21  is a perspective view of a prismatic reflector used in combination with any of the centrifugal separation chambers of  FIGS. 10-17 ; 
         FIG. 22  is a perspective view of the prismatic reflector of  FIG. 21 , showing light being transmitted therethrough; 
         FIGS. 23-26  are diagrammatic views of the ramp and prismatic reflector of the centrifugal separation chamber passing through the path of light from the light source during a calibration phase; 
         FIGS. 27-30  are diagrammatic views of the voltage output or signal transmitted by the light detector during the conditions shown in  FIGS. 23-26 , respectively; 
         FIGS. 31-34  are diagrammatic views of the ramp and prismatic reflector passing through the path of light from the light source during a separation procedure; 
         FIGS. 35-38  are diagrammatic views of the voltage output or signal transmitted by the light detector during the conditions shown in  FIGS. 31-34 , respectively; 
         FIGS. 39 and 40  are diagrammatic views of separated blood components on the ramp and the pulse widths of a signal generated by the light detector for each condition; 
         FIG. 41  is a diagrammatic view of saline on the ramp and the pulse width of a signal generated by the light detector for such a condition; 
         FIG. 42  is a diagrammatic view of the position of an interface between separated blood components on the ramp compared to a target interface position; and 
         FIGS. 43-58  are schematic views of the fluid circuit of  FIG. 2 , showing the system carrying out different fluid flow tasks in connection with separation and collection of mononuclear cells and T-cells, followed by genome editing and (optionally) washing of the T-cells. 
     
    
    
     DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     The embodiments disclosed herein are for the purpose of providing a description of the present subject matter, and it is understood that the subject matter may be embodied in various other forms and combinations not shown in detail. Therefore, specific designs and features disclosed herein are not to be interpreted as limiting the subject matter as defined in the accompanying claims. 
       FIGS. 1-58  show components of a blood or fluid separation system that embodies various aspects of the present subject matter. Generally speaking, the system includes two principal components, a durable and reusable blood separation device  10  ( FIG. 1 ) and a disposable fluid flow circuit  12  ( FIG. 2 ). The blood separation device  10  includes a spinning membrane separator drive unit  14  ( FIG. 1 ), a centrifuge or centrifugal separator  16  ( FIG. 3 ), additional components that control fluid flow through the disposable flow circuit  12 , and a controller  18  ( FIG. 1 ), which governs the operation of the other components of the blood separation device  10  to perform a blood processing and collection procedure selected by the operator, as will be described in greater detail 
     I. The Durable Blood Separation Device 
     The blood separation device  10  ( FIG. 1 ) is configured as a durable item that is capable of long-term use. It should be understood that the blood separation device  10  of  FIG. 1  is merely exemplary of one possible configuration and that blood separation devices according to the present disclosure may be differently configured. 
     In the illustrated embodiment, the blood separation device  10  is embodied in a single housing or case  20 . The illustrated case  20  includes a generally horizontal portion  22  (which may include an inclined or angled face or upper surface for enhanced visibility and ergonomics) and a generally vertical portion  24 . The spinning membrane separator drive unit  14  and the centrifugal separator  16  are shown as being incorporated into the generally horizontal portion  22  of the case  20 , while the controller  18  is shown as being incorporated into the generally vertical portion  24 . The configuration and operation of the spinning membrane separator drive unit  14 , the centrifugal separator  16 , the controller  18 , and selected other components of the blood separation device  10  will be described in greater detail. 
     In the illustrated embodiment, the generally horizontal portion  22  is intended to rest on an elevated, generally horizontal support surface (e.g., a countertop or a tabletop), but it is also within the scope of the present disclosure for the case  20  to include a support base to allow the case  20  to be appropriately positioned and oriented when placed onto a floor or ground surface. It is also within the scope of the present disclosure for the case  20  to be mounted to a generally vertical surface (e.g., a wall), by either fixedly or removably securing the generally vertical portion  24  of the case  20  to the surface. 
     The case  20  may be configured to assume only the position or configuration of  FIG. 1  or may be configured to move between two or more positions or configurations. For example, in one embodiment, the generally horizontal and vertical portions  22  and  24  are joined by a hinge or pivot, which allows the case  20  to be moved between a functional or open configuration ( FIG. 1 ) in which the generally vertical portion  24  is oriented at approximately 90 degrees to the generally horizontal portion  22  and a transport or closed configuration in which the generally vertical portion  24  is rotated about the hinge to approach the generally horizontal portion  22 . In such a reconfigurable embodiment, the generally vertical portion  24  may be considered to be the lid of the case  20 , while the generally horizontal portion  22  may be considered to be the base. If the case  20  is so reconfigurable, then it may include a latch for releasably locking the case  20  in its closed configuration and/or a handle, which the operator can grasp for transporting the case  20  in its closed configuration. 
     While it may be advantageous for the blood separation device  10  to be embodied in a compact, portable case  20 , it is also within the scope of the present disclosure for the blood separation device to be embodied in a larger case or fixture that is intended to be installed in a single location and remain in that location for an extended period of time. If the blood separation device is provided as a fixture, it may be provided with more components and functionality than a more portable version. 
     A. Spinning Membrane Separator Drive Unit 
     The illustrated blood separation device  10  includes a spinner support or spinning membrane separator drive unit  14  ( FIG. 1 ) for accommodating a generally cylindrical spinning membrane separator  26  of the fluid flow circuit  12 . U.S. Pat. No. 5,194,145 describes an exemplary spinning membrane separator drive unit that would be suitable for incorporation into the blood separation device  10 , but it should be understood that the spinning membrane separator drive unit  14  may be differently configured without departing from the scope of the present disclosure. 
     The illustrated spinning membrane separator drive unit  14  has a base  28  configured to receive a lower portion of the spinning membrane separator  26  and an upper end cap  30  to receive an upper portion of the spinning membrane separator  26 . Preferably, the upper end cap  30  is positioned directly above the base  28  to orient a spinning membrane separator  26  received by the spinning membrane separator drive unit  14  vertically and to define a vertical axis about which the spinning membrane separator  26  is spun. While it may be advantageous for the spinning membrane separator drive unit  14  to vertically orient a spinning membrane separator  26 , it is also within the scope of the present disclosure for the spinning membrane separator  26  to be differently oriented when mounted to the blood separation device  10 . 
     In one embodiment, one of the components of the spinning membrane separator drive unit  14  is movable with respect to the other component, which may allow differently sized spinning membrane separators  26  to be received by the spinning membrane separator drive unit  14 . For example, the upper end cap  30  may be translated vertically with respect to the base  28  and locked in a plurality of different positions, with each locking position corresponding to a differently sized spinning membrane separator  26 . 
     At least one of the base  28  and the upper end cap  30  is configured to spin one or more components of the spinning membrane separator  26  about the axis defined by the spinning membrane separator drive unit  14 . The mechanism by which the spinning membrane separator drive unit  14  spins one or more components of the spinning membrane separator  26  may vary without departing from the scope of the present disclosure. In one embodiment, a component of the spinning membrane separator  26  to be spun includes at least one element configured to be acted upon by a magnet (e.g., a metallic material), while the spinning membrane separator drive unit  14  includes a magnet (e.g., a series of magnetic coils or semi-circular arcs). By modulating the magnetic field acting upon the aforementioned element of the spinning membrane separator  26 , the component or components of the spinning membrane separator  26  may be made to spin in different directions and at varying speeds. In other embodiments, different mechanisms may be employed to spin the component or components of the spinning membrane separator  26 . 
     Regardless of the mechanism by which the spinning membrane separator drive unit  14  spins the component or components of the spinning membrane separator  26 , the component or components of the spinning membrane separator  26  is preferably spun at a speed that is sufficient to create Taylor vortices in a gap between the spinning component and a stationary component of the spinning membrane separator  26  (or a component that spins at a different speed). Fluid to be separated within the spinning membrane separator  26  flows through this gap, and filtration may be dramatically improved by the creation of Taylor vortices. 
     B. Centrifugal Separator 
     As for the centrifugal separator  16 , it includes a centrifuge compartment  32  that may receive the other components of the centrifugal separator  16  ( FIG. 3 ). The centrifuge compartment  32  may include a lid  34  that is opened to insert and remove a centrifugal separation chamber  36  of the fluid flow circuit  12 . During a separation procedure, the lid  34  may be closed with the centrifugal separation chamber  36  positioned within the centrifuge compartment  32 , as the centrifugal separation chamber  36  is spun or rotated about an axis  38  under the power of an electric drive motor or rotor  40  of the centrifugal separator  16 . 
     The particular configuration and operation of the centrifugal separator  16  depends upon the particular configuration of the centrifugal separation chamber  36  of the fluid flow circuit  12 . In one embodiment, the centrifugal separator  16  is similar in structure and operation to that of the ALYX system manufactured by Fenwal, Inc. of Lake Zurich, Ill., which is an affiliate of Fresenius Kabi AG of Bad Homburg, Germany, as described in greater detail in U.S. Pat. No. 8,075,468, which is incorporated herein by reference. More particularly, the centrifugal separator  16  may include a carriage or support  42  that holds the centrifugal separation chamber  36  and a yoke member  44 . The yoke member  44  engages an umbilicus  46  of the fluid flow circuit  12 , which extends between the centrifugal separation chamber  36  and a cassette  48  of the fluid flow circuit  12  ( FIG. 4 ). The yoke member  44  causes the umbilicus  46  to orbit around the centrifugal separation chamber  36  at a one omega rotational speed. The umbilicus  46  twists about its own axis as it orbits around the centrifugal separation chamber  36 . The twisting of the umbilicus  46  about its axis as it rotates at one omega with the yoke member  44  imparts a two omega rotation to the centrifugal separation chamber  36 , according to known design. The relative rotation of the yoke member  44  at a one omega rotational speed and the centrifugal separation chamber  36  at a two omega rotational speed keeps the umbilicus  46  untwisted, avoiding the need for rotating seals. 
     Blood is introduced into the centrifugal separation chamber  36  by the umbilicus  46 , with the blood being separated (e.g., into a layer of less dense components, such as platelet-rich plasma, and a layer of more dense components, such as packed red blood cells) within the centrifugal separation chamber  36  as a result of centrifugal forces as it rotates. Components of an interface monitoring system may be positioned within the centrifuge compartment  32  to oversee separation of blood within the centrifugal separation chamber  36 . As shown in  FIGS. 5-7 , the interface monitoring system may include a light source  50  and a light detector  52 , which is positioned and oriented to receive at least a portion of the light emitted by the light source  50 . Preferably, the light source  50  and the light detector  52  are positioned on stationary surfaces of the centrifuge compartment  32 , but it is also within the scope of the present disclosure for one or both to be mounted to a movable component of the centrifugal separator  16  (e.g., to the yoke member  44 , which rotates at a one omega speed). 
     The orientation of the various components of the interface monitoring system depends at least in part on the particular configuration of the centrifugal separation chamber  36 , which will be described in greater detail herein. In general, though, the light source  50  emits a light beam (e.g., a laser light beam) through the separated blood components within the centrifugal separation chamber  36  (which may be formed of a material that substantially transmits the light or at least a particular wavelength of the light without absorbing it). A portion of the light reaches the light detector  52 , which transmits a signal to the controller  18  that is indicative of the location of an interface between the separated blood components. If the controller  18  determines that the interface is in the wrong location (which can affect the separation efficiency of the centrifugal separator  16  and/or the quality of the separated blood components), then it can issue commands to the appropriate components of the blood separation device  10  to modify their operation so as to move the interface to the proper location. 
     C. Other Components of the Blood Separation Device 
     In addition to the spinning membrane separator drive unit  14  and the centrifugal separator  16 , the blood separation device  10  may include other components compactly arranged to aid blood processing. 
     The generally horizontal portion  22  of the case  20  of the illustrated blood separation device  10  includes a cassette station  54 , which accommodates a cassette  48  of the fluid flow circuit  12  ( FIG. 4 ). In one embodiment, the cassette station  54  is similarly configured to the cassette station of U.S. Pat. No. 5,868,696 (which is incorporated herein by reference), but is adapted to include additional components and functionality. The illustrated cassette station  54  includes a plurality of clamps or valves V 1 -V 9  ( FIG. 1 ), which move between a plurality of positions (e.g., between a retracted or lowered position and an actuated or raised position) to selectively contact or otherwise interact with corresponding valve stations C 1 -C 9  of the cassette  48  of the fluid flow circuit  12  ( FIGS. 2 and 4 ). Depending on the configuration of the fluid flow circuit  12 , its cassette  48  may not include a valve station C 1 -C 9  for each valve V 1 -V 9  of the cassette station  54 , in which case fewer than all of the valves V 1 -V 9  will be used in a separation procedure. 
     In the actuated position, a valve V 1 -V 9  engages the associated valve station C 1 -C 9  to prevent fluid flow through that valve station C 1 -C 9  (e.g., by closing one or more ports associated with the valve station C 1 -C 9 , thereby preventing fluid flow through that port or ports). In the retracted position, a valve V 1 -V 9  is disengaged from the associated valve station C 1 -C 9  (or less forcefully contacts the associated valve station C 1 -C 9  than when in the actuated position) to allow fluid flow through that valve station C 1 -C 9  (e.g., by opening one or more ports associated with the valve station C 1 -C 9 , thereby allowing fluid flow through that port or ports). Additional clamps or valves V 10  and V 11  may be positioned outside of the cassette station  52  to interact with portions or valve stations C 10  and C 11  (which may be lengths of tubing) of the fluid flow circuit  12  to selectively allow and prevent fluid flow therethrough. The valves V 1 -V 9  and corresponding valve stations C 1 -C 9  of the cassette station  54  and cassette  48  may be differently configured and operate differently from the valves V 10  and V 11  and valve stations C 10  and C 11  that are spaced away from the cassette station  54 . 
     The cassette station  54  may be provided with additional components, such as pressure sensors A 1 -A 4 , which interact with sensor stations S 1 -S 4  of the cassette  48  to monitor the pressure at various locations of the fluid flow circuit  12 . For example, if the blood source is a human donor, one or more of the pressure sensors A 1 -A 4  may be configured to monitor the pressure of the donor&#39;s vein during blood draw and return. Other pressure sensors A 1 -A 4  may monitor the pressure of the spinning membrane separator  26  and the centrifugal separation chamber  36 . The controller  18  may receive signals from the pressure sensor A 1 -A 4  that are indicative of the pressure within the fluid flow circuit  12  and, if a signal indicates a low- or high-pressure condition, the controller  18  may initiate an alarm or error condition to alert an operator to the condition and/or to attempt to bring the pressure to an acceptable level without operator intervention. 
     The blood separation device  10  may also include a plurality of pumps P 1 -P 6  (which may be collectively referred to as a pump assembly) cause fluid to flow through the fluid flow circuit  12 . The pumps P 1 -P 6  may be differently or similarly configured and/or function similarly or differently from each other. In the illustrated embodiment, the pumps P 1 -P 6  are configured as peristaltic pumps, which may be generally configured as described in U.S. Pat. No. 5,868,696. Each pump P 1 -P 6  engages a different tubing loop T 1 -T 6  extending from a side surface of the cassette  48  ( FIG. 4 ) and may be selectively operated under command of the controller  18  to cause fluid to flow through a portion of the fluid flow circuit  12 , as will be described in greater detail. In one embodiment, all or a portion of the cassette station  54  may be capable of translational motion in and out of the case  20  to allow for automatic loading of the tubing loops T 1 -T 6  into the associated pump P 1 -P 6 . 
     The illustrated blood separation device  10  also includes a centrifugal separator sensor M 1  for determining one or more properties of fluids flowing out of and/or into the centrifugal separator  16 . If the fluid flowing out of the centrifugal separator  16  includes red blood cells, the centrifugal separator sensor M 1  may be configured to determine the hematocrit of the fluid. If the fluid flowing out of the centrifugal separator  16  is platelet-rich plasma, the centrifugal separator sensor M 1  may be configured to determine the platelet concentration of the platelet-rich plasma. The centrifugal separator sensor M 1  may detect the one or more properties of a fluid by optically monitoring the fluid as it flows through tubing of the fluid flow circuit  12  or by any other suitable approach. The controller  18  may receive signals from the centrifugal separator sensor M 1  that are indicative of the one or more properties of fluid flowing out of the centrifugal separator  16  and use the signals to optimize the separation procedure based upon that property or properties. If the property or properties is/are outside of an acceptable range, then the controller  18  may initiate an alarm or error condition to alert an operator to the condition. A suitable device and method for monitoring hematocrit and/or platelet concentration is described in U.S. Pat. No. 6,419,822 (which is incorporated herein by reference), but it should be understood that a different approach may also be employed for monitoring hematocrit and/or platelet concentration of fluid flowing out of the centrifugal separator  16 . 
     The illustrated blood separation device  10  further includes a spinner outlet sensor M 2 , which accommodates tubing of the fluid flow circuit  12  that flows a separated substance out of the spinning membrane separator  26 . The spinner outlet sensor M 2  monitors the substance to determine one or more properties of the substance, and may do so by optically monitoring the substance as it flows through the tubing or by any other suitable approach. For example, a supernatant or a combination of a supernatant, platelets, and smaller red blood cells may flow through the tubing as a waste product, in which case the spinner outlet sensor M 2  may be configured to monitor the optical characteristics of the waste product for quality purposes, such as monitoring for cell loss or hemolysis. 
     The illustrated blood separation device  10  also includes an air detector M 3  (e.g., an ultrasonic bubble detector), which accommodates tubing of the fluid flow circuit  12  that flows fluid to a recipient. It may be advantageous to prevent air from reaching the recipient, so the air detector M 3  may transmit signals to the controller  18  that are indicative of the presence or absence of air in the tubing. If the signal is indicative of air being present in the tubing, the controller  18  may initiate an alarm or error condition to alert an operator to the condition and/or to take corrective action to prevent the air from reaching the recipient (e.g., by reversing the flow of fluid through the tubing or diverting flow to a vent location). 
     The generally vertical portion  24  of the case  18  may include a plurality of weight scales W 1 -W 6  (six are shown, but more or fewer may be provided), each of which may support one or more fluid containers F 1 -F 7  of the fluid flow circuit  12  ( FIG. 2 ). The containers F 1 -F 7  receive blood components or waste products separated during processing or intravenous fluids or additive fluids. Each weight scale W 1 -W 6  transmits to the controller  18  a signal that is indicative of the weight of the fluid within the associated container F 1 -F 7  to track the change of weight during the course of a procedure. This allows the controller  18  to process the incremental weight changes to derive fluid processing volumes and flow rates and subsequently generate signals to control processing events based, at least in part, upon the derived processing volumes. For example, the controller  18  may diagnose leaks and obstructions in the fluid flow circuit  12  and alert an operator. 
     The illustrated case  20  is also provided with a plurality of hooks or supports H 1  and H 2  that may support various components of the fluid flow circuit  12  or other suitably sized and configured objects. 
     D. Controller 
     According to an aspect of the present disclosure, the blood separation device  10  includes a controller  18 , which is suitably configured and/or programmed to control operation of the blood separation device  10 . In one embodiment, the controller  18  comprises a main processing unit (MPU), which can comprise, e.g., a Pentium™ type microprocessor made by Intel Corporation, although other types of conventional microprocessors can be used. In one embodiment, the controller  18  may be mounted inside the generally vertical portion  24  of the case  20 , adjacent to or incorporated into an operator interface station (e.g., a touchscreen). In other embodiments, the controller  18  and operator interface station may be associated with the generally horizontal portion  22  or may be incorporated into a separate device that is connected (either physically, by a cable or the like, or wirelessly) to the blood separation device  10 . 
     The controller  18  is configured and/or programmed to execute at least one blood processing application but, more advantageously, is configured and/or programmed to execute a variety of different blood processing applications. For example, the controller  18  may be configured and/or programmed to carry out one or more of the following: a double unit red blood cell collection procedure, a plasma collection procedure, a plasma/red blood cell collection procedure, a red blood cell/platelet/plasma collection procedure, a platelet collection procedure, a platelet/plasma collection procedure, and (as will be described in detail herein) an MNC collection procedure. Additional or alternative procedure applications can be included without departing from the scope of the present disclosure. 
     More particularly, in carrying out any one of these blood processing applications, the controller  18  is configured and/or programmed to control one or more of the following tasks: drawing blood into a fluid flow circuit  12  mounted to the blood separation device  10 , conveying blood through the fluid flow circuit  12  to a location for separation (i.e., into a spinning membrane separator  26  or centrifugal separation chamber  36  of the fluid flow circuit  12 ), separating the blood into two or more components as desired, and conveying the separated components into storage containers, to a second location for further separation (e.g., into whichever of the spinning membrane separator  26  and centrifugal separation chamber  36  that was not used in the initial separation stage), or to a recipient (which may be the source from which the blood was originally drawn). 
     This may include instructing the spinning membrane separator drive unit  14  and/or the centrifugal separator  16  to operate at a particular rotational speed and instructing a pump P 1 -P 6  to convey fluid through a portion of the fluid flow circuit  12  at a particular flow rate. Hence, while it may be described herein that a particular component of the blood separation device  10  (e.g., the spinning membrane separator drive unit  14  or the centrifugal separator  16 ) performs a particular function, it should be understood that that component is being controlled by the controller  18  to perform that function. 
     As will be described, a procedure may call for the use of both the centrifugal separator  16  and the spinning membrane separator drive unit  14 , in which case a properly programmed controller  18  is especially important to coordinate the operation of these two components, along with the other components of the blood separation device  10  to ensure that flow to and from the centrifugal separator  16  and spinning membrane separator drive unit  14  is at the proper level and that the components are functioning properly to process the blood circulating through the fluid flow circuit  12 . 
     Before, during, and after a procedure, the controller  18  may receive signals from various components of the blood separation device  10  (e.g., the pressure sensors A 1 -A 4 ) to monitor various aspects of the operation of the blood separation device  10  and characteristics of the blood and separated blood components as they flow through the fluid flow circuit  12 . If the operation of any of the components and/or one or more characteristics of the blood or separated blood components is outside of an acceptable range, then the controller  18  may initiate an alarm or error condition to alert the operator and/or take action to attempt to correct the condition. The appropriate corrective action will depend upon the particular error condition and may include action that is carried out with or without the involvement of an operator. 
     For example, the controller  18  may include an interface control module, which receives signals from the light detector  52  of the interface monitoring system. The signals that the controller  18  receives from the light detector  52  are indicative of the location of an interface between the separated blood components within the centrifugal separation chamber  36 . If the controller  18  determines that the interface is in the wrong location, then it can issue commands to the appropriate components of the blood separation device  10  to modify their operation so as to move the interface to the proper location. For example, the controller  18  may instruct one of the pumps P 1 -P 6  to cause blood to flow into the centrifugal separation chamber  36  at a different rate and/or for a separated blood component to be removed from the centrifugal separation chamber  36  at a different rate and/or for the centrifugal separation chamber  36  to be spun at a different speed by the centrifugal separator  16 . A particular protocol carried out by the interface control module in adjusting the position of the interface within the centrifugal separation chamber  36  will be described in greater detail with respect to an exemplary centrifugal separation chamber  36 . 
     If provided, an operator interface station associated with the controller  18  allows the operator to view on a screen or display (in alpha-numeric format and/or as graphical images) information regarding the operation of the system. The operator interface station also allows the operator to select applications to be executed by the controller  18 , as well as to change certain functions and performance criteria of the system. If configured as a touchscreen, the screen of the operator interface station can receive input from an operator via touch-activation. Otherwise, if the screen is not a touchscreen, then the operator interface station may receive input from an operator via a separate input device, such as a computer mouse or keyboard. It is also within the scope of the present disclosure for the operator interface station to receive input from both a touchscreen and a separate input device, such as a keypad. 
     II. The Disposable Fluid Flow Circuit 
     A. Overview 
     As for the fluid flow circuit or flow set  12  ( FIG. 2 ), it is intended to be a sterile, single use, disposable item. Before beginning a given blood processing and collection procedure, the operator loads various components of the fluid flow circuit  12  in the case  20  in association with the blood separation device  10 . The controller  18  implements the procedure based upon preset protocols, taking into account other input from the operator. Upon completing the procedure, the operator removes the fluid flow circuit  12  from association with the blood separation device  10 . The portions of the fluid flow circuit  12  holding the collected blood component or components (e.g., collection containers or bags) are removed from the case  20  and retained for storage, transfusion, or further processing. The remainder of the fluid flow circuit  12  is removed from the case  20  and discarded. 
     A variety of different disposable fluid flow circuits may be used in combination with the blood separation device  10 , with the appropriate fluid flow circuit depending on the separation procedure to be carried out using the system. Generally speaking, though, the fluid flow circuit  12  includes a cassette  48  ( FIG. 4 ), to which the other components of the fluid flow circuit  12  are connected by flexible tubing. The other components may include a plurality of fluid containers F 1 -F 7  (for holding blood, a separated blood component, an intravenous fluid, or an additive solution, for example), one or more blood source access devices (e.g., a connector for accessing blood within a fluid container), and a spinning membrane separator  26  ( FIGS. 8 and 9 ) and/or a centrifugal separation chamber  36  ( FIGS. 10-17 ). 
     B. Cassette And Tubing 
     The cassette  48  ( FIG. 4 ) provides a centralized, programmable, integrated platform for all the pumping and many of the valving functions required for a given blood processing procedure. In one embodiment, the cassette  48  is similarly configured to the cassette of U.S. Pat. No. 5,868,696, but is adapted to include additional components (e.g., more tubing loops T 1 -T 6 ) and functionality. 
     In use, the cassette  48  is mounted to the cassette station  54  of the blood separation device  10 , with a flexible diaphragm of the cassette  48  placed into contact with the cassette station  54 . The flexible diaphragm overlays an array of interior cavities formed by the body of the cassette  48 . The different interior cavities define sensor stations S 1 -S 4 , valve stations C 1 -C 9 , and a plurality of flow paths. The side of the cassette  48  opposite the flexible diaphragm may be sealed by another flexible diaphragm or a rigid cover, thereby sealing fluid flow through the cassette  48  from the outside environment. 
     Each sensor station S 1 -S 4  is aligned with an associated pressure sensor A 1 -A 4  of the cassette station  54 , with each pressure sensor A 1 -A 4  capable of monitoring the pressure within the associated sensor station S 1 -S 4 . Each valve station C 1 -C 9  is aligned with an associated valve V 1 -V 9 , and may define one or more ports that allow fluid communication between the valve station C 1 -C 9  and another interior cavity of the cassette  48  (e.g., a flow path). As described above, each valve V 1 -V 9  is movable under command of the controller  18  to move between a plurality of positions (e.g., between a retracted or lowered position and an actuated or raised position) to selectively contact the valve stations C 1 -C 9  of the cassette  48 . In the actuated position, a valve V 1 -V 9  engages the associated valve station C 1 -C 9  to close one or more of its ports to prevent fluid flow therethrough. In the retracted position, a valve V 1 -V 9  is disengaged from the associated valve station C 1 -C 9  (or less forcefully contacts the associated valve station C 1 -C 9  than when in the actuated position) to open one or more ports associated with the valve station C 1 -C 9 , thereby allowing fluid flow therethrough. 
     As described, a plurality of tubing loops T 1 -T 6  extend from the side surface of the cassette  48  to interact with pumps P 1 -P 6  of the blood separation device  10 . In the illustrated embodiment, six tubing loops T 1 -T 6  extend from the cassette  48  to be received by a different one of six pumps P 1 -P 6 , but in other embodiments, a procedure may not require use of all of the pumps P 1 -P 6 , in which case the cassette  48  may include fewer than six tubing loops. The different pumps P 1 -P 6  may interact with the tubing loops T 1 -T 6  of the cassette  48  to perform different tasks during a separation procedure (as will be described in greater detail), but in one embodiment, a different one of the pumps P 1 -P 6  may be configured to serve as an anticoagulant pump P 1 , a source pump P 2 , a recirculation pump P 3 , a transfer pump P 4 , a plasma pump P 5 , and a waste pump P 6 . Certain procedures require fewer than all of the sensor stations, valve stations, and/or tubing loops illustrated in the exemplary cassette  48  of  FIG. 4 , such that it should be understood that the cassettes of different fluid flow circuits  12  may be differently configured (e.g., with fewer sensor stations, valve stations, and/or tubing loops) without departing from the scope of the present disclosure. 
     Additional tubing extends from the side surface of the cassette  48  to connect to the other components of the fluid flow circuit  12 , such as the various fluid containers F 1 -F 5 , the spinning membrane separator  26 , and the centrifugal separation chamber  36 . The number and content of the various fluid containers F 1 -F 7  depends upon the procedure for which the fluid flow circuit  12  is used, with the fluid containers F 1 -F 7  of one particular fluid flow circuit  12  and procedure being described in greater detail herein. If the fluid flow circuit  12  includes a centrifugal separation chamber  36 , then the tubing connected to it (which includes one inlet tube and two outlet tubes) may be aggregated into an umbilicus  46  ( FIG. 3 ) that is engaged by the yoke member  44  of the centrifugal separator  16  (as described above) to cause the umbilicus  46  to orbit around and spin or rotate the centrifugal separation chamber  36  during a separation procedure. 
     Various additional components may be incorporated into the tubing leading out of the cassette  48  or into one of the cavities of the cassette  48 . For example, as shown in  FIG. 2 , a manual clamp  56  may be associated with a line or lines leading to the blood source and/or fluid recipient, a return line filter  58  (e.g., a microaggregate filter) may be associated with a line leading to a fluid recipient, filters (not illustrated) may be positioned upstream of one or more of the fluid containers to remove a substance (e.g., leukocytes) from a separated component (e.g., red blood cells or platelets) flowing into the fluid container, and/or an air trap  62  may be positioned on a line upstream of the centrifugal separation chamber  36 . 
     C. Spinning Membrane Separator 
     Turning to  FIGS. 8 and 9 , a spinning membrane separator  26  is shown. As will be described in greater detail, the spinning membrane separator  26  may be used for washing a mononuclear cell product (including T-cell lymphocytes). The spinning membrane separator  26  is associated with the remainder of the fluid flow circuit  12  by an inlet port  64  and two outlet ports  66  and  68 . The inlet port  64  is shown as being associated with a bottom end or portion of the spinning membrane separator  26 , while the outlet ports  66  and  68  are associated with an upper end or portion of the spinning membrane separator  26 , but it is within the scope of the present disclosure for the spinning membrane separator  26  to be inverted, with fluid entering an upper end or portion of the spinning membrane separator  26  and fluid exiting a lower end or portion of the spinning membrane separator  26 . 
     The illustrated spinning membrane separator  26  includes a generally cylindrical housing  70  mounted concentrically about a longitudinal vertical central axis. An internal member or rotor  72  is mounted concentrically with the central axis. The housing  70  and rotor  72  are relatively rotatable, as described above with respect to the spinning membrane separator drive unit  14 . In a preferred embodiment, the housing  70  is stationary and the rotor  72  is a rotating spinner that is rotatable concentrically within the cylindrical housing  70 . In such an embodiment, the housing  70  (or at least its upper and lower ends) are formed of non-magnetic material, while the rotor  72  includes an element (e.g., a metallic material) that interacts with a magnet of the spinning membrane separator drive unit  14  to rotate the rotor  72  within the housing  70 , as described above. 
     The boundaries of the blood flow path are generally defined by the gap  74  between the interior surface of the housing  70  and the exterior surface of the rotor  72 , which is sometimes referred to as the shear gap. A typical shear gap  74  may be approximately 0.025-0.050 inches (0.067-0.127 cm) and may be of a uniform dimension along the axis, for example, where the axis of the housing  70  and rotor  72  are coincident. Alternatively, the width of the shear gap  74  also may vary along the axial direction, for example with the width of the gap  74  increasing in the direction of flow to limit hemolysis. Such a gap width may range from about 0.025 to about 0.075 inches (0.06-0.19 cm). For example, in one embodiment, the axes of the housing  70  and rotor  72  are coincident, with the outer diameter of the rotor  72  decreasing in the direction of flow, while the inner diameter of the housing  70  remaining constant. In other embodiments, the inner diameter of the housing  70  may increase while the outer rotor diameter remains constant or both surfaces may vary in diameter. In one exemplary embodiment, the gap width may be about 0.035 inches (0.088 cm) at the upstream or inlet end of the gap  74  and about 0.059 inches (0.15 cm) at the downstream end or terminus of the gap  74 . The gap width could change linearly or stepwise or in some other manner as may be desired. In any event, the width dimension of the gap  74  is preferably selected so that at the desired relative rotational speed, Taylor-Couette flow, such as Taylor vortices, are created in the gap  74  and hemolysis is limited. 
     A fluid to be washed is fed into the gap  74  by the inlet port  64  ( FIG. 8 ), which directs the fluid into the fluid flow entrance region at or adjacent to the bottom end of the spinning membrane separator  26 . The spinning membrane separator drive unit  14  causes relative rotation of the housing  70  and rotor  72 , creating Taylor vortices within the gap  74 . The outer surface of the rotor  72  and/or the inner surface of the housing  70  is at least partially (and more preferably, substantially or entirely) covered by a cylindrical porous membrane  76  (shown in  FIG. 9  as being mounted to the outer surface of the rotor  72 ). It should be, thus, understood that the term “spinning membrane separator” does not necessarily require that the membrane  76  is mounted to a component of the spinning membrane separator  26  that spins, but may also include a device in which the membrane  76  is mounted to a stationary component that includes another component that rotates with respect to the stationary membrane  76 . 
     The membrane  76  typically has a nominal pore size that may vary, depending on the nature of the substances to be removed. For example, if only a supernatant is to be filtered out during cell washing of an MNC product, then a nominal pore size of 0.65-0.8 microns may be employed. In another example, in which supernatant, platelets, and some smaller red blood cells are to be filtered out, a nominal pore size of 4.0 microns may be advantageous. It should be understood that these are only exemplary and that membranes having other pore sizes may alternatively be used without departing from the scope of the present disclosure. Membranes useful in the methods described herein may be fibrous mesh membranes, cast membranes, track-etched membranes or other types of membranes that will be known to those of skill in the art. For example, in one embodiment, the membrane  76  may have a polyester mesh (substrate) with nylon particles solidified thereon, thereby creating a tortuous path through which only certain sized components will pass. In another embodiment, the membrane  76  may be made of a thin (approximately 15 micron thick) sheet of, for example, polycarbonate with pores or holes defined therein that are sized and configured to allow passage of only a selected one or more blood components. 
     In an embodiment in which the rotor  72  spins within the housing  70  and the membrane  76  is mounted to the outer surface of the rotor  72 , the outer surface of the rotor  72  may be shaped to define a series of spaced-apart circumferential grooves or ribs  78  separated by annular lands  80  ( FIG. 9 ). The surface channels defined by the circumferential grooves  78  are interconnected by longitudinal grooves  82 . At one or both ends of the rotor  72 , these grooves  78  are in communication with a central orifice or manifold  84 . Pumping fluid into and out of the spinning membrane separator  26  causes the substance being filtered out (e.g., a supernatant) to flow through the membrane  76  and grooves  78 , while the while remainder of the fluid (e.g., T-cells) remains within the gap  74  as fluid flows from the inlet port  64  at the bottom portion of the spinning membrane separator  26  toward the upper portion. Relative rotation of the rotor  72  and housing  70  causes a particular flow pattern within the gap  74  (described above) that enables filtration without clogging the membrane  76 . 
     At the upper portion of the spinning membrane separator  26 , the substance being filtered out (e.g., the supernatant) exits the spinning membrane separator  26  via an outlet port  66  that is concentric with the rotational axis and in fluid communication with the central orifice  84  of the rotor  72  ( FIG. 9 ), with the substance flowing into a line associated with the outlet port  66 . The remainder of the fluid (e.g., the T-cells) exits the gap  74  via an outlet port  68  defined in the upper end or portion of the housing  70  and oriented generally tangentially to the gap  74  ( FIG. 8 ), flowing into a line associated with the outlet port  68 . 
     As described above, it may be advantageous to use differently sized spinning membrane separators  26  depending on the particular blood separation procedure being carried out.  FIG. 8  shows a spinning membrane separator  26  having a rotor  72  with a spinner diameter D, a filtration length FL, and an overall length  LOA . An exemplary smaller spinning membrane separator may have a spinner diameter D of approximately 1.1″, a filtration length FL of approximately 3″, and an overall length  LOA  of approximately 5.0″. By comparison, an exemplary larger spinning membrane separator may have a spinner diameter D of approximately 1.65″, a filtration length FL of approximately 5.52″, and an overall length  LOA  of approximately 7.7″. An exemplary smaller spinning membrane separator is described in greater detail in U.S. Pat. No. 5,194,145, while an exemplary larger spinning membrane separator is described in greater detail in U.S. Patent Application Publication No. 2015/0218517, which is incorporated herein by reference. 
     D. Centrifugal Separation Chamber 
     A fluid flow circuit  12  may be provided with a centrifugal separation chamber  36  if platelets, white blood cells, and/or (as described herein) MNCs are to be separated and collected. An exemplary centrifugal separation chamber  36   a  is shown in  FIGS. 10 and 11 , while  FIG. 12  illustrates the fluid flow path defined by the centrifugal separation chamber  36   a . In the illustrated embodiment, the body of the centrifugal separation chamber  36   a  is pre-formed in a desired shape and configuration (e.g., by injection molding) from a rigid, biocompatible plastic material, such as a non-plasticized medical grade acrylonitrile-butadiene-styrene (ABS). All contours, ports, channels, and walls that affect the blood separation process are preformed in a single, injection molded operation. Alternatively, the centrifugal separation chamber  36   a  can be formed by separate molded parts, either by nesting cup-shaped subassemblies or two symmetric halves. 
     The underside of the centrifugal separation chamber  36   a  includes a shaped receptacle  86  that is suitable for receiving an end of the umbilicus  46  of the fluid flow circuit  12  ( FIG. 3 ). A suitable receptacle  86  and the manner in which the umbilicus  46  may cooperate with the receptacle  86  to deliver fluid to and remove fluid from the centrifugal separation chamber  36   a  are described in greater detail in U.S. Pat. No. 8,075,468. 
     The illustrated centrifugal separation chamber  36   a  has radially spaced apart inner (low-g) and outer (high-g) side wall portions  88  and  90 , a bottom or first end wall portion  92 , and a cover or second end wall portion  93 . The cover  93  comprises a simple flat part that can be easily welded or otherwise secured to the body of the centrifugal separation chamber  36   a . Because all features that affect the separation process are incorporated into one injection molded component, any tolerance differences between the cover  93  and the body of the centrifugal separation chamber  36   a  will not affect the separation efficiencies of the centrifugal separation chamber  36   a . The wall portions  88  and  90 , the bottom  92 , and the cover  93  together define an enclosed, generally annular channel  94  ( FIG. 12 ). 
     The (whole blood) inlet  96  communicating with the channel  94  is defined between opposing interior radial walls  98  and  100 . One of the interior walls  98  joins the outer (high-g) wall portion  90  and separates the upstream and downstream ends of the channel  94 . The interior walls  98  and  100  define the inlet passageway  96  of the centrifugal separation chamber  36   a  which, in one flow configuration, allows fluid to flow from the umbilicus  46  to the upstream end of the channel  94 . 
     The illustrated centrifugal separation chamber  36   a  further includes first and second outlets  102  and  104 , respectively, which may be defined by opposing surfaces of interior radial walls. Both the first and second outlets  102  and  104  extend radially inward from the channel  94 . The first (plasma) outlet  102  extends radially inward from an opening which, in the illustrated embodiment, is located at the inner side wall portion  88 , while the second (red blood cell) outlet  104  extends radially inward from an opening that is associated with the outer side wall portion  90 . The illustrated first outlet  102  is positioned adjacent to the inlet  96  (near the upstream end of the channel  94 ), while the second outlet  104  may be positioned at the opposite, downstream end of the channel  94 . 
     It should be understood that the centrifugal separation chamber  36   a  illustrated in  FIG. 10  is merely exemplary and that the centrifugal separation chamber  36  may be differently configured without departing from the scope of the present disclosure. For example,  FIGS. 13 and 14  show an alternative embodiment of a centrifugal separation chamber  36   b , while  FIG. 15  illustrates the fluid flow path defined by the centrifugal separation chamber  36   b . The centrifugal separation chamber  36   b  is similar to the centrifugal separation chamber  36   a  except for the location at which the inlet  96  opens into the channel  94 . In the centrifugal separation chamber  36   a  of  FIG. 10 , the inlet  96  opens into the channel  94  adjacent to the first end wall portion  92  (while the outlets  102  and  104  open into the channel  94  adjacent to the second end wall portion  93 ), as best shown in  FIGS. 11 and 12 . In contrast, the inlet  96  of the centrifugal separation chamber  36   b  of  FIG. 13  opens into the channel  94  adjacent to the second end wall portion  93  (along with the outlets  102  and  104 ), as best shown in  FIGS. 14  and  15 . The location at which the inlet  96  opens into the channel  94  may affect the separation of fluid within the channel  94 , so the centrifugal separation chamber  36   a  of  FIG. 10  may be preferable for certain procedures or for use in combination with certain blood separation devices, while the centrifugal separation chamber  36   b  of  FIG. 13  may be preferable for other procedures or for use in combination with other blood separation devices. 
       FIGS. 16 and 17  show another exemplary embodiment of a centrifugal separation chamber  36   c  suitable for incorporation into a fluid flow circuit  12 . The centrifugal separation chamber  36   c  is similar to the centrifugal separation chambers  36   a  and  36   b  of  FIGS. 10 and 13  except for the location at which the inlet  96  opens into the channel  94 . In contrast to the inlets  96  of the centrifugal separation chambers  36   a  and  36   b  of  FIGS. 10 and 13 , the inlet  96  of the centrifugal separation chamber  36   c  of  FIG. 16  opens into the channel  94  at an intermediate axial location that is spaced from the first and second end wall portion  92  and  93  (while the outlets  102  and  104  open into the channel adjacent to the second end wall portion  93 ), as best shown in  FIG. 17 . The inlet  96  may open into the channel  94  at a location that is closer to the first end wall portion  92  than to the second end wall portion  93 , at a location that is closer to the second end wall portion  93  than to the first end wall portion  92 , or at a location that is equally spaced between the first and second end wall portions  92  and  93 . The axial location at which the inlet  96  opens into the channel  94  may affect the separation of fluid within the channel  94 , so the preferred location at which the inlet  96  opens into the channel  94  (which may also depend upon the nature of the blood separation device paired with the centrifugal separation chamber  36   c ) may be experimentally determined. 
     1. Centrifugal Separation and Interface Detection Principles 
     Blood flowed into the channel  94  separates into an optically dense layer RBC and a less optically dense layer PLS ( FIGS. 18-20 ) as the centrifugal separation chamber  36  is rotated about the rotational axis  38 . The optically dense layer RBC forms as larger and/or heavier blood particles move under the influence of centrifugal force toward the outer (high-g) wall portion  90 . The optically dense layer RBC will typically include red blood cells (and, hence, may be referred to herein as the “RBC layer”) but, depending on the speed at which the centrifugal separation chamber  36  is rotated, other cellular components (e.g., larger white blood cells) may also be present in the optically dense layer RBC. 
     The less optically dense layer PLS typically includes a plasma constituent, such as platelet-rich plasma or platelet-poor plasma (and, hence, will be referred to herein as the “PLS layer”). Depending on the speed at which the centrifugal separation chamber  36  is rotated and the length of time that the blood is resident therein, other components (e.g., smaller white blood cells and anticoagulant) may also be present in the less optically dense layer PLS. 
     In one embodiment, blood introduced into the channel  94  via the inlet  96  will travel in a generally clockwise direction (in the orientation of  FIG. 10 ) as the optically dense layer RBC separates from the less optically dense layer PLS. The optically dense layer RBC continues moving in the clockwise direction as it travels the length of the channel  94  along the outer side wall portion  90 , from the upstream end to the downstream end, where it exits the channel  94  via the second outlet  104 . The less optically dense layer PLS separated from the optically dense layer RBC reverses direction, moving counterclockwise along the inner side wall portion  88  to the first outlet  102 , adjacent to the inlet  96 . The inner side wall portion  88  may be tapered inward as it approaches the second outlet  104  to force the plasma liberated at or adjacent to the downstream end of the channel  94  to drag the interface back towards the upstream end of the channel  94 , where the lower surface hematocrit will re-suspend any platelets settled on the interface. 
     As described above, the transition between the optically dense layer RBC and the less optically dense layer PLS may be referred to as the interface INT. In one embodiment, the interface INT contains mononuclear cells and T-cell lymphocytes. The location of the interface INT within the channel  94  of the centrifugal separation chamber  36  can dynamically shift during blood processing, as  FIGS. 18-20  show. If the location of the interface INT is too high (that is, if it is too close to the inner side wall portion  88  and the first outlet  102 , as in  FIG. 19 ), red blood cells can flow into the first outlet  102 , potentially adversely affecting the quality of the low density components (platelet-rich plasma or platelet-poor plasma). On the other hand, if the location of the interface INT is too low (that is, if it resides too far away from the inner wall portion  88 , as  FIG. 20  shows), the collection efficiency of the system may be impaired. The ideal or target interface INT may be experimentally determined, which may vary depending on any of a number of factors (e.g., the configuration of the centrifugal separation chamber  36 , the rate at which the centrifugal separation chamber  36  is rotated about the rotational axis  38 , etc.). As will be described herein, it may be advantageous to temporarily move the interface INT away from the location of  FIG. 18  during a separation procedure. 
     As described above, the blood separation device  10  may include an interface monitoring system and a controller  18  with an interface control module to monitor and, as necessary, correct the position of the interface INT. In one embodiment, the centrifugal separation chamber  36  is formed with a ramp  106  extending from the high-g wall portion  90  at an angle α across at least a portion of the channel  94  ( FIGS. 10 and 18-20 ). The angle α, measured with respect to the rotational axis  38  is about 25° in one embodiment.  FIGS. 18-20  show the orientation of the ramp  106  when viewed from the low-g side wall portion  88  of the centrifugal separation chamber  36 . Although it describes a flexible separation chamber, the general structure and function of the ramp  106  may be better understood with reference to U.S. Pat. No. 5,632,893, which is incorporated herein by reference. The ramp  106  may be positioned at any of a number of locations between the upstream and downstream ends of the channel  94 , but in one embodiment, the ramp  106  may be positioned generally adjacent to the first outlet  102 , in the path of fluid and/or a fluid component moving from the inlet  96  to the first outlet  102 . 
     The ramp  106  makes the interface INT between the optically dense layer RBC and the less optically dense layer PLS more discernible for detection, displaying the optically dense layer RBC, less optically dense layer PLS, and interface INT for viewing through a light-transmissive portion of the centrifugal separation chamber  36 . To that end, the ramp  106  and at least the portion of the centrifugal separation chamber  36  angularly aligned with the ramp  106  may be formed of a light-transmissive material, although it may be advantageous for the entire centrifugal separation chamber  36  to be formed of the same light-transmissive material. 
     In the illustrated embodiment, the light source  50  of the interface monitoring system is secured to a fixture or wall of the centrifuge compartment  32  and oriented to emit a light that is directed toward the rotational axis  38  of the centrifugal separator  16 , as shown in  FIGS. 5-7 . If the light detector  52  is positioned at an angle with respect to the light source  50  (as in the illustrated embodiment), the light L emitted by the light source  50  must be redirected from its initial path before it will reach the light detector  52 . In the illustrated embodiment, the light L is redirected by a reflector that is associated with a light-transmissive portion of the inner side wall portion  88 , as shown in  FIGS. 5 and 6 . The reflector may be a separate piece that is secured to the inner side wall portion  88  (e.g., by being bonded thereto) or may be integrally formed with the body of the centrifugal separation chamber  36 . 
     In one embodiment, the reflector may be a reflective surface, such as a mirror, that is oriented (e.g., at a 45° angle) to direct light L emitted by the light source  50  to the light detector  52 . In another embodiment, the reflector is provided as a prismatic reflector  108  ( FIGS. 7, 21, and 22 ), which is formed of a light-transmissive material (e.g., a clear plastic material) and has inner and outer walls  110  and  112  and first and second end walls  114  and  116  ( FIG. 21 ). The inner wall  110  is positioned against the inner side wall portion  88  of the centrifugal separation chamber  36  and is oriented substantially perpendicular to the initial path of the light L from the light source  50 . This allows light L from the light source  50  to enter into the prismatic reflector  108  via the inner wall  110  while continuing along its initial path. The light L continues through the prismatic reflector  108  along its initial path until it encounters the first end wall  114 . The first end wall  114  is oriented at an angle (e.g., an approximately 45° angle) with respect to the first surface  110  and the second end wall  116 , causing the light to be redirected within the prismatic reflector  108 , rather than exiting the prismatic reflector  108  via the first end wall  114 . 
     The first end wall  114  directs the light L at an angle to its initial path (which may be an approximately 90° angle, directing it from a path toward the rotational axis  38  to a path that is generally parallel to the rotational axis  38 ) toward the second end wall  116  ( FIG. 22 ). The first end wall  114  and the inner and outer walls  110  and  112  of the prismatic reflector  108  may be configured to transmit the redirected light L from the first end wall  114  to the second end wall  116  by total internal reflection. The second end wall  116  is oriented substantially perpendicular to the redirected path of the light L through the prismatic reflector  108 , such that the light L will exit the prismatic reflector  108  via the second end wall  116 , continuing along its redirected path. In one embodiment, the second end wall  116  is roughened or textured or otherwise treated or conditioned to diffuse the light L as it exits the prismatic reflector  108 , which may better ensure that the light L reaches the light detector  52  ( FIG. 7 ). 
     The prismatic reflector  108  may be angularly aligned with the ramp  106 , such that the light L from the light source  50  will only enter into the prismatic reflector  108  when the ramp  106  has been rotated into the path of the light L. At all other times (when the ramp  106  is not in the path of the light L), the light L will not reach the prismatic reflector  108  and, thus, will not reach the light detector  52 . This is illustrated in  FIGS. 23-26 , which show the ramp  106  and prismatic reflector  108  as the centrifugal separation chamber  36  is rotated about the rotational axis  38  (while the light source  50  remains in a fixed location). In  FIG. 23 , the ramp  106  and prismatic reflector  108  have not yet been rotated into the initial path of the light L from the light source  50 . At this time, no light is transmitted to the light detector  52 , such that the output voltage of the light detector  52  (i.e., the signal transmitted from the light detector  52  to the controller  18 ) is in a low- or zero-state ( FIG. 27 ). 
     Upon the ramp  106  first being rotated into the initial path of the light L from the light source  50  ( FIG. 24 ), the light L will begin to reach the prismatic reflector  108 , which directs the light L to the light detector  52 . This causes the voltage output of the light detector  52  (i.e., the signal transmitted from the light detector  52  to the controller  18 ) to increase to a non-zero value or state, as shown in  FIG. 28 . 
     During a calibration phase, the channel  94  is filled with a fluid that will transmit the light L rather than absorbing or reflecting the light or otherwise preventing the light L from reaching the prismatic reflector  108 , such that the voltage output of the light detector  52  will remain generally constant as the ramp  106  and prismatic reflector  108  are rotated through the initial path of the light L from the light source  50  ( FIGS. 25 and 29 ). Such a calibration phase may coincide with a priming phase during which saline is pumped through the fluid flow circuit  12  to prime the fluid flow circuit  12  or may comprise a separate phase. A calibration phase may be useful in ensuring the proper operation of the light source  50  and the light detector  52 , standardizing the readings taken during a separation procedure in case of any irregularities or imperfections of the centrifugal separation chamber  36 , and establishing a baseline value for the signal transmitted from the light detector  52  to the controller  18  when the ramp  106  and prismatic reflector  108  are aligned with the light source  50 . As will be described in greater detail, the voltage output of the light detector  52  will typically not remain constant as the ramp  106  and prismatic reflector  108  are rotated through the initial path of the light L from the light source  50  because the different fluid layers displayed on the ramp  106  will allow different amounts of light L to reach the prismatic reflector  108 . 
     The ramp  106  and prismatic reflector  108  are eventually rotated out of alignment with the light source  50  ( FIG. 26 ), at which time no light L will reach the prismatic reflector  108  and the voltage output of the light detector  52  will return to its low- or zero-state ( FIG. 30 ). 
     It may be advantageous for the light L to have a relatively small diameter for improved resolution of the signal that is generated by the light detector  52 . 
     2. Exemplary Interface Detection and Correction Procedure 
     During separation of blood within the channel  94 , the light L from the light source  50  travels through a light-transmissive portion of the outer side wall portion  90  and the ramp  106  to intersect the separated blood components thereon when the ramp  106  has been rotated into the initial path of the light L. After passing through the ramp  106 , the light continues through the channel  94  and the fluids in the channel  94 . At least a portion of the light L (i.e., the portion not absorbed or reflected by the fluids) exits the channel  94  by striking and entering a light-transmissive portion of the inner side wall portion  88 . The light L passes through the inner side wall portion  88  and enters the prismatic reflector  108 , which redirects the light L from its initial path to the light detector  50 , as described above. Thus, it will be seen that the light L reaches the light detector  52  after intersecting and traveling through the separated blood components in the channel  94  only once, in contrast to known systems in which light from a light source travels through a ramp and a fluid-filled channel before being reflected back through the channel to reach a light detector. Requiring the light L to traverse the fluid-filled channel  94  only once before reaching the light detector  52  instead of twice may be advantageous in that it tends to increase the intensity of the light L that reaches the light detector  52 , which may improve monitoring and correction of the interface location. 
     The light detector  52  generates a signal that is transmitted to the interface control module of the controller  18 , which can determine the location of the interface INT on the ramp  106 . In one embodiment, the location of the interface INT is associated with a change in the amount of light L that is transmitted through the less optically dense layer PLS and the optically dense layer RBC. For example, the light source  50  may be configured to emit a light L that is more readily transmitted by platelet-rich plasma or platelet-poor plasma than by red blood cells, such as red visible light (from a laser or a differently configured light source  50 ), which is substantially absorbed by red blood cells. The less optically dense layer PLS and the optically dense layer RBC each occupy a certain portion of the ramp  106 , with the light detector  52  receiving different amounts of light L depending on whether the light L travels through the less optically dense layer PLS on the ramp  106  or the optically dense layer RBC on the ramp  106 . The percentage of the ramp  106  occupied by each layer is related to the location of the interface INT in the channel  94 . Thus, by measuring the amount of time that the voltage output or signal from the light detector  52  is relatively high (corresponding to the time during which the light L is passing through only the less optically dense layer PLS on the ramp  106 ), the controller  18  may determine the location of the interface INT and take steps to correct the location of the interface INT, if necessary. 
       FIGS. 31-34  show a portion of the ramp  106  being rotated into and through the initial path of the light L from the light source  50 . Four specific events are shown: just before the ramp  106  is rotated into the path of the light L ( FIG. 31 ), the ramp  106  first being rotated into the path of the light L ( FIG. 32 ), just before the interface INT displayed on the ramp  106  is rotated into the path of the light L ( FIG. 33 ), and just after the interface INT is rotated into the path of the light L ( FIG. 34 ).  FIGS. 35-38  respectively illustrate the voltage output of the light detector  52  (corresponding to the signal that it transmits to the controller  18 ) during each of these events. 
     As described above, the light detector  52  will receive no light L from the light source  50  when the prismatic reflector  108  is out of alignment with the initial path of the light L from the light source  50 , as shown in  FIG. 29 .  FIG. 35  shows that the output voltage of the light detector  52  (i.e., the signal transmitted from the light detector  52 ) to the controller  18 ) at this time is in a low- or zero-state. 
     When the ramp  106  is first rotated into the path of light L from the light source  50  ( FIG. 32 ), the light detector  52  may begin receiving light L. The amount of light L received by the light detector  52  depends upon the fluid on the ramp  106  encountered by the light L (i.e., the fluid in the channel  94  between the ramp  106  and the inner side wall portion  88  that the light L must traverse before being directed to the light detector  52 ). As described above, the less optically dense layer PLS occupies a certain percentage of the channel  94  adjacent to the inner side wall portion  88 , while the optically dense layer RBC occupies a certain percentage of the channel  94  adjacent to the outer side wall portion  90  (with the interface INT positioned at the transition between the two separated blood component layers). The illustrated ramp  106  is closest to the inner side wall portion  88  at its left end (in the orientation of  FIGS. 31-34 ), while being farther spaced from the inner side wall portion  88  at its right end. At and adjacent to its left end, the ramp  106  will display only the fluid positioned closest to the inner side wall portion  88  (i.e., the less optically dense layer PLS), while the ramp  106  will display only the fluid positioned closest to the outer side wall portion  90  (i.e., the optically dense layer RBC) at and adjacent to its right end, as shown in  FIGS. 31-34 . At some point between its ends, the angled ramp  106  will be at a radial position where it will display the transition between the less optically dense layer PLS and the optically dense layer RBC (i.e., the interface INT). Hence, the location of the interface INT on the ramp  106  is dependent upon the percentage of the width of the ramp  106  that displays the less optically dense layer PLS (which is indicative of the percentage of the channel  94  occupied by the less optically dense layer PLS) and the percentage of the width of the ramp  106  that displays the optically dense layer RBC (which is indicative of the percentage of the channel  94  occupied by the optically dense layer RBC). It should be understood that the percentage of the ramp  106  occupied by the less optically dense layer PLS and by the optically dense layer RBC is not necessarily equal to the percentage of the channel  94  occupied by the less optically dense layer PLS and by the optically dense layer RBC, but that the percentage of the ramp  106  occupied by a separated blood component layer may be merely indicative of the percentage of the channel  94  occupied by that separated blood component layer. 
     In such an embodiment, as the ramp  106  is rotated into the path of the light L from the light source  50 , the light L will first encounter the portion of the ramp  106  that is positioned closest to the inner side wall portion  88  (i.e., the section of the ramp  106  that most restricts the channel  94 ), as shown in  FIG. 32 . As described above, the less optically dense layer PLS will be positioned adjacent to the inner side wall portion  88  as it separates from the optically dense layer RBC, such that the fluid displayed on this radially innermost section of the ramp  106  (i.e., the fluid present in the channel  94  between the ramp  106  and the inner side wall portion  88 ) will be the less optically dense layer PLS. The light is substantially transmitted through the less optically dense layer PLS to the inner side wall portion  88 , and through the light-transmissive inner side wall portion  88  to the prismatic reflector  108 , which redirects the light L to the light detector  52 . This causes the voltage output of the light detector  52  (i.e., the signal transmitted from the light detector  52  to the controller  18 ) to increase to a non-zero value or state, as shown in  FIG. 36 . Depending on the nature of the light L, the amount of light L received by the light detector  52  (and, hence, the magnitude of the voltage output) after the light L has passed through the less optically dense layer PLS may be greater than, less than, or equal to the amount of light L received by the light detector  52  after passing through saline during the calibration phase described above. 
     Further rotation of the ramp  106  through the path of light L from the light source  50  exposes the light L to portions of the ramp  106  that are increasingly spaced from the inner side wall portion  88  (i.e., the light L travels through portions of the channel  94  that are less restricted by the ramp  106  as the ramp  106  is rotated through the path of the light L). Up until the time that the interface INT on the ramp  106  is rotated into the path of the light L (as shown in  FIG. 33 ), the only fluid in the channel  94  that the light L will have passed through will be the less optically dense layer PLS, such that a generally uniform level of light reaches the light detector  52  between the conditions shown in  FIGS. 32 and 33 . Accordingly, the voltage output of the light detector  52  will be generally uniform (at an elevated level) the whole time that the ramp  106  passes through the path of the light L before being exposed to the interface INT, as shown in  FIG. 37 . The controller  18  may be programmed and/or configured to consider a signal that deviates from a maximum signal level (e.g., a 10% decrease) to be part of the elevated signal for purposes of calculating the pulse width of the signal. The controller  18  will treat a greater deviation (i.e., a greater decrease in the magnitude of the signal) as the end of the elevated signal for purposes of calculating the pulse width of the signal. 
     Just after the interface INT has been rotated into the path of light L from the light source  50 , the light L will begin to encounter the optically dense layer RBC in the channel  94 , as shown in  FIG. 34 ). As described above, the optically dense layer RBC will be positioned adjacent to the outer side wall portion  90  as it separates from the less optically dense layer PLS, such that the optically dense layer RBC will not be displayed on the ramp  106  until the ramp  106  is spaced a greater distance away from the inner side wall portion  88  (i.e., toward the right end of the ramp  106  in the orientation of  FIGS. 31-34 ). Less light L is transmitted through the optically dense layer RBC than through the less optically dense layer PLS (which may include all or substantially all of the light L being absorbed by the optically dense layer RBC), such that the amount of light L that reaches the light detector  52  will decrease compared to the amount of light L that reaches the light detector  52  while traveling through only the less optically dense layer PLS in the channel  94  ( FIGS. 32 and 33 ). 
     When receiving less light L, the voltage output or signal from the light detector  52  will decrease to a lower level than when the light L was passing through only the less optically dense layer PLS in the channel  94 , as shown in  FIG. 38 . When the light L encounters the optically dense layer RBC in the channel  94 , the light detector  52  may be generating a signal or voltage output that is approximately equal to its zero-state (as in  FIG. 35 , when the light detector  52  is receiving no light L) or a signal or voltage output that is some degree less than the magnitude of the signal or voltage output generated while the light L encounters only the less optically dense layer PLS in the channel  94 . The controller  18  may be programmed and/or configured to recognize this lower level signal as representing the presence of the optically dense layer RBC on the ramp  106  (and in the portion of the channel  94  being traversed by the light L) and treat this lower level signal as the end point of the elevated signal generated by the light detector  52  while light L passes through only the less optically dense layer PLS in the channel  94 . 
     Thus, the pulse width of the elevated signal from the light detector  52  to the controller  18  (i.e., the time during which light L is traversing only the less optically dense layer PLS in the channel  94 ) is determined by the percentages of the ramp  106  that are occupied by the less optically dense layer PLS and the optically dense layer RBC. Accordingly, a greater pulse width of the signal from the light detector  52  to the controller  18  is associated with the less optically dense layer PLS occupying a larger portion of the ramp  106  (as shown in  FIG. 39  from the point of view of the light source  50 , which may correspond to the condition shown in  FIG. 19 ) and will be indicative of a thinner optically dense layer RBC on the ramp  106  (and in the channel  94 ). Conversely, a signal from the light detector  52  to the controller  18  having a narrower pulse width is associated with the less optically dense layer PLS occupying a smaller portion of the ramp  106  (as shown in  FIG. 40 ) and will be indicative of a thicker optically dense layer RBC on the ramp  106  (and in the channel  94 ). 
     The controller  18  may compare the pulse width of the signal to the pulse width generated during the calibration phase (described above and shown in  FIG. 41 ), which corresponds to the pulse width when light L is transmitted to the light detector  52  over the entire width of the ramp  106 . The pulse width of the signal generated by the light detector  52  during the calibration phase may be referred to as the saline calibration signal. Comparing these two pulse widths will indicate the percentage of the ramp  106  that is occupied by the less optically dense layer PLS and by the optically dense layer RBC, which information the controller  18  may use to determine the location of the interface INT within the channel  94 . In particular, the interface position may be calculated as follows: 
       Interface position (%)=((saline calibration pulse width−current plasma pulse width)/saline calibration pulse width)*100  [Equation 1]
 
     It will be seen that Equation 1 effectively calculates the percentage of the ramp  106  that is occupied by the optically dense layer RBC, as the difference between the two pulse widths corresponds to the length of time that the ramp  106  is rotated through the path of the light L without the light detector  52  received an elevated level of light L (i.e., the amount of time that the ramp  106  is rotated through the path of the light L while the optically dense layer RBC is present on the ramp  106 ). 
     When the location of the interface INT on the ramp  106  has been determined, the interface control module compares the actual interface location with a desired interface location, which may be referred to as the setpoint S. The difference between the setpoint S and the calculated interface position may be referred to as the error signal E, which is shown in  FIG. 42 . It should be understood that so expressing the error signal E in terms of a targeted red blood cell percentage value (i.e., the percentage of the ramp  106  that is actually occupied by the optically dense layer RBC vs. the percentage of the ramp  106  which should be occupied by the optically dense layer RBC) is merely exemplary, and that the error signal E may be expressed or calculated in any of a number of other ways. 
     When the control value is expressed in terms of a targeted red blood cell percentage value, a negative error signal E indicates that the optically dense layer RBC on the ramp  106  is too large (as  FIG. 19  shows). The interface control module of the controller  18  generates a signal to adjust an operational parameter accordingly, such as by reducing the rate at which platelet-rich plasma is removed through the first outlet  102  under action of a pump of the blood separation device  10 . The interface INT moves toward the desired control position (as  FIG. 18  shows), where the error signal is zero. 
     A positive error signal indicates that the optically dense layer RBC on the ramp  106  is too small (as  FIGS. 20 and 42  show). The interface control module of the controller  18  generates a signal to adjust an operational parameter accordingly, such as by increasing the rate at which the plasma constituent is removed through the first outlet  102  under action of a pump of the blood separation device  10 . The interface INT moves toward the desired control position ( FIG. 18 ), where the error signal is again zero. 
     It should be understood that this system for controlling the location of the interface INT is merely exemplary and that differently configured and/or functioning systems may be employed without departing from the scope of the present disclosure. 
     III. Exemplary Separation Procedure 
     An exemplary blood separation procedure that may be carried out using systems and techniques according to the present disclosure will now be described. 
     Depending on the blood separation objectives, there is a suitable procedure for separating and collecting any of a variety of different blood components, either alone or in combination with other blood components. Accordingly, prior to processing, an operator selects the desired protocol (e.g., using an operator interface station, if provided), which informs the controller  18  of the manner in which it is to control the other components of the blood separation device  10  during the procedure. 
     The operator may also proceed to enter various parameters, such as information regarding the blood source. In one embodiment, the operator also enters the target yield for the various blood components (which may also include entering a characteristic of the blood, such as a platelet pre-count) or some other collection control system (e.g., the amount of whole blood to be processed). 
     If there are any fluid containers (e.g., a storage solution container) that are not integrally formed with the fluid flow circuit  12 , they may be connected to the fluid flow circuit  12  (e.g., by piercing a septum of a tube of the fluid flow circuit  12  or via a luer connector), with the fluid flow circuit  12  then being mounted to the blood separation device  10  (including the fluid containers F 1 -F 7  being hung from the weight scales W 1 -W 6  and the hooks or supports H 1  and H 2 , as appropriate). An integrity check of the fluid flow circuit  12  may be executed by the controller  18  to ensure the various components are properly connected and functioning. Following a successful integrity check, the blood source is connected to the fluid flow circuit  12  and the fluid flow circuit  12  may be primed (e.g., by saline pumped from a saline bag F 2  by operation of one or more of the pumps P 1 -P 6  of the blood separation device  10 ). 
     When the fluid flow circuit  12  has been primed, blood separation may begin. The stages of blood separation vary depending on the particular procedure, and will be described in greater detail below. 
     A. T-Cell Lymphocyte Collection 
     According to one aspect of the present disclosure, the blood separation device  10  may be used to separate and collect mononuclear cells and T-cell lymphocytes as an MNC product. Following collection, the MNC product may be mixed with a formulation containing genetic material and passed through an electroporation device, which enables genetic editing of the T-cells of the MNC product. The MNC product may be washed before and/or after being passed through the electroporation device. 
     1. Fluid Flow Circuit 
       FIG. 2  is a schematic view of an exemplary fluid flow circuit  12  having a pair of blood access devices (e.g., needles) for separating and collecting mononuclear cells and T-cell lymphocytes from blood as an MNC product. The fluid flow circuit  12  includes a cassette  48  of the type described above and illustrated in  FIG. 4 , which connects the various components of the fluid flow circuit  12 . The various connections amongst the components of the fluid flow circuit  12  are shown in  FIG. 2 , which also shows the fluid flow circuit  12  mounted to the blood separation device  10 . 
     Components of the fluid flow circuit  12  interact with many of the components of the blood separation device  10 , as will be described, but there are selected components of the blood separation device  10  that are not used in separating and collecting mononuclear cells and T-cells using the fluid flow circuit  12  of  FIG. 2 . Most notably, one of the pressure sensors A 3  is not used in the procedure described herein. The fluid flow circuit  12  includes a fluid container F 3  (which may be referred to as a first waste bag) that, in the illustrated procedures of  FIGS. 43-58 , is only used during the pre-processing priming phase, in which saline from the saline bag F 2  is pumped through the fluid flow circuit  12  to prime it, before being conveyed to the first waste bag F 3  for disposal at the end of the procedure. 
     2. MNC Collection Phase 
     Blood is drawn into the fluid flow circuit  12  from a blood source (e.g., using a needle) via line L 1 , as shown in  FIG. 43 . The line L 1  may include a manual clamp  56  that may initially be in a closed position to prevent fluid flow through the line L 1 . When processing is to begin, an operator may move the manual clamp  56  from its closed position to an open position to allow fluid flow through the line L 1 . 
     The blood is drawn into the line L 1  by the source pump P 2 . Anticoagulant from the anticoagulant bag F 1  may be added to the blood via line L 2  by action of the anticoagulant pump P 1 . The valve V 10  associated with valve station C 10  is open to allow flow through line L 1 , while the valve V 3  associated with valve station C 3  is closed to prevent flow through line L 3 , thereby directing the blood toward the centrifugal separation chamber  36  via lines L 1  and L 4 . Prior to reaching the centrifugal separation chamber  36 , the blood may pass through the air trap  62 , the sensor station S 2  associated with pressure sensor A 2 , and the centrifugal separator sensor M 1 . The centrifugal separator sensor M 1  may detect the hematocrit of the fluid entering the centrifugal separation chamber  36  (which may be used to set the flow rate of the plasma pump P 5 ), while the pressure sensor A 2  may monitor the pressure in the centrifugal separation chamber  36 . 
     The centrifugal separator  16  of the blood separation device  10  manipulates the centrifugal separation chamber  36  of the fluid flow circuit  12  to separate the blood in the centrifugal separation chamber  36  into platelet-rich plasma and packed red blood cells, with a mononuclear cell-containing layer or interface positioned therebetween. While the interface is referred to herein as the mononuclear cell-containing layer, it should be understood that it also contains T-cell lymphocytes, which are to be collected with the mononuclear cells as an MNC product. Granulocytes may tend to move into the same layers as the packed red blood cells, rather than remaining in the mononuclear cell-containing layer. In one embodiment, the centrifugal separation chamber  36  is rotated nominally at 4,500 rpm, but the particular rotational speed may vary depending on the flow rates of fluids into and out of the centrifugal separation chamber  36 . 
     The packed red blood cells (and granulocytes) exit the centrifugal separation chamber  36  via line L 5 . The valve V 4  associated with line L 6  is closed, such that the packed red blood cells are directed through line L 7 . Valve V 2  associated with line L 8  is closed, while valve V 1  is open to direct the packed red blood cells through line L 9 , the return line filter  58 , air detector M 3 , and the valve station C 11  associated with open valve V 11  on their way to a recipient (which is typically the blood source). 
     Platelet-rich plasma is drawn out of the centrifugal separation chamber  36  via line L 10  by the combined operation of the recirculation pump P 3  and the plasma pump P 5 . The platelet-rich plasma travels through line L 10  until it reaches a junction, which splits into lines L 11  and L 12 . The recirculation pump P 3 , which is associated with line L 11 , redirects a portion of the platelet-rich plasma to a junction, where it mixes with blood in line L 4  that is being conveyed into the centrifugal separation chamber  36  by the source pump P 2 . Recirculating a portion of the platelet-rich plasma into the centrifugal separation chamber  36  with inflowing blood decreases the hematocrit of the blood entering the centrifugal separation chamber  36 , which may improve separation efficiency of the platelets from the red blood cells. By such an arrangement, the flow rate of the fluid entering the centrifugal separation chamber  36  is equal to the sum of the flow rates of the source pump P 2  and the recirculation pump P 3 . 
     As the platelet-rich plasma drawn out of the centrifugal separation chamber  36  into line L 11  by the recirculation pump P 3  is immediately added back into the centrifugal separation chamber  36 , the bulk or net platelet-rich plasma flow rate out of the centrifugal separation chamber  36  is equal to the flow rate of the plasma pump P 5 . Line L 12  has a junction, where it splits into lines L 13  and L 14 , with line L 14  itself including a junction, where it splits into lines L 15  and L 16 . A valve V 7  associated with valve station C 7  is closed to prevent fluid flow through the line L 16 , while the transfer pump P 4  associated with line L 15  is inactive, thereby directing the separated platelet-rich plasma through line L 13  and the valve station C 6  associated with open valve V 6 . Line L 13  includes a junction downstream of valve station C 6 , where it splits into lines L 17  and L 18 . The valve V 5  associated with valve station C 5  is closed to prevent fluid flow through line L 15 , thereby directing the separated platelet-rich plasma through line L 18 . The platelet-rich plasma in line L 18  combines with the packed red blood cells in line L 9 , with the platelet-rich plasma being conveyed to a recipient (as described above with respect to the packed red blood cells) with the packed red blood cells as a combined fluid. 
     The mononuclear cell-containing layer remains within the centrifugal separation chamber  36  and increases in volume throughout this phase while the packed red blood cells and the platelet-rich plasma are removed from the centrifugal separation chamber  36 . This phase continues for a predetermined amount of time or until the occurrence of a predetermined event. In one embodiment, this phase continues until a predetermined volume of blood (e.g., 1,000-2,000 ml) has been processed, which is experimentally determined to be the blood volume that can be processed before mononuclear cells begin to escape the centrifugal separation chamber  36 . 
     Toward the end of the MNC collection phase, the valve V 1  associated with valve station C 1  is closed, while the valve V 4  associated with valve station C 4  is opened, as shown in  FIG. 44 . This prevents the packed red blood cells from being conveyed to the recipient (e.g., the blood source) and instead directs the packed red blood cells through line L 6  and into the red blood cell collection container F 4 . This phase lasts long enough to collect a specific volume of packed red blood cells, which are used to transfer the mononuclear cell-containing layer out of the centrifugal separation chamber  36 , as will be described in greater detail herein. In one embodiment, approximately 50 ml of packed red blood cells is collected, although the particular volume may vary without departing from the scope of the present disclosure. 
     3. MNC Transfer Phase 
     When the target volume of packed red blood cells has been collected, the MNC transfer phase begins. This phase may begin by allowing the centrifugal separator  16  to rotate the centrifugal separation chamber  36  without flow for approximately 30-60 seconds to allow the mononuclear cell distribution along the interface between the platelet-rich plasma and the red blood cell layer in the centrifugal separation chamber  36  to stabilize. 
     Blood draw is stopped during the MNC transfer phase by closing the valve V 10  associated with valve station C 10 , while also ceasing operation of the anticoagulant pump P 1  and the source pump P 2 , as shown in  FIG. 45 . The valve V 3  associated with valve station C 3  is opened to allow saline to flow out of the saline container F 2  via gravity. The saline flows through line L 3  and to the blood source via line L 1  to prevent coagulation of any blood present in the fistula of line L 1  that has not yet been anticoagulated. 
     To transfer the mononuclear cell-containing layer out of the centrifugal separation chamber  36 , the thickness of the red blood cell layer is increased until it forces the mononuclear cell-containing layer out of the centrifugal separation chamber  36 . This is done by ceasing operation of the recirculation pump P 3 , while the plasma pump P 5  continues to operate. This pulls the packed red blood cells in the red blood cell collection container F 4  via line L 6 . On account of valves V 1  and V 2  being closed, the packed red blood cells are directed back into the centrifugal separation chamber  36  via line L 5  (i.e., via the red blood cell outlet). 
     The centrifugal separator  16  continues to rotate the centrifugal separation chamber  36  at the same speed as during the MNC collection phase (e.g., approximately 4,500 rpm), such that the returning packed red blood cells quickly increase the thickness of the red blood cell layer within the centrifugal separation chamber  36 . This causes the mononuclear cell-containing layer on top of the red blood cell layer to exit the centrifugal separation chamber  36  via line L 10  (i.e., the plasma outlet). It should be understood that no fluid will exit the centrifugal separation chamber  36  via line L 4  (i.e., the inlet) due to the source pump P 2  and the recirculation pump P 3  being inactive. 
     The centrifugal separator sensor M 1  detects the optical density and/or the redness of the fluid exiting the centrifugal separation chamber  36  via line L 10 . Initially, platelet-rich plasma will be exiting the centrifugal separation chamber  36  via line L 10 , in which case the centrifugal separator sensor M 1  will observe low optical density and/or low redness. While platelet-rich plasma is exiting the centrifugal separation chamber  36  via line L 10 , the valve V 7  associated with valve station C 7  will be closed to prevent fluid flow through line L 16 , with the transfer pump P 4  being inactive to prevent fluid flow through line L 15 . The valve V 6  associated with valve station C 6  is open, thus directing the platelet-rich plasma through line L 13  for receipt by a recipient (e.g., the blood source), as described above. 
     Once the centrifugal separator sensor M 1  detects a sufficient number of mononuclear cells exiting the centrifugal separation chamber  36  via line L 10  (which corresponds to an increase in the optical density and redness of the fluid flowing through the plasma outlet), the valve V 7  associated with valve station C 7  opens and the valve V 6  associated with valve station C 6  closes, as shown in  FIG. 46 . This will direct the fluid in line L 10  (i.e., the mononuclear cell-containing layer) through lines L 14  and L 16  and into the MNC collection container F 5 . 
     Once the centrifugal separator sensor M 1  detects that the fluid in line L 10  is packed red blood cells (due to detection of an elevated optical density and/or redness level), this phase is ended to prevent packed red blood cells from flowing into the MNC collection container F 5 . 
     It should be noted that the collected red blood cells are conveyed into the centrifugal separation chamber  36  via the red blood cell outlet (i.e., line L 5 ) to harvest mononuclear cells and T-cell lymphocytes. This is in contrast to conventional approaches, in which collected red blood cells instead enter a blood separation chamber via a whole blood inlet to harvest mononuclear cells. The approach described herein may be advantageous to the extent that a second inlet (or a fluid flow path between the red blood cell collection container and the whole blood inlet) are not required, which may reduce the number of components of the fluid flow circuit  12  and its complexity. 
     It should also be understood that operating the plasma pump P 5  to pull the contents of the red blood cell collection container back into the centrifugal separation chamber  36  via the red blood cell outlet is only one possible approach. In another embodiment, a pump may be associated with line L 5  to instead push the contents of the red blood cell collection container back into the centrifugal separation chamber  36  via line L 5 . 
     4. Plasma Flush Phase 
     Upon completion of the MNC transfer phase, lines L 10  and L 12  will contain mostly packed red blood cells (which were used to push the mononuclear cell-containing layer out of the centrifugal separation chamber  36 ), while lines L 14  and L 16  will contain mononuclear cells and T-cell lymphocytes that were not conveyed all the way into the MNC collection container F 5 . To collect the mononuclear cells and T-cells in lines L 14  and L 16 , a plasma flush phase is executed. 
     The plasma flush phase begins by first closing the valves V 4  and V 7  associated with valve stations C 4  and C 7  (respectively), opening the valve V 6  associated with valve station C 6 , and reestablishing separation. For an initial predetermined amount of time (e.g., approximately 10-20 seconds), anticoagulated blood is drawn into the centrifugal separation chamber  36  and separated (as in the MNC collection phase of  FIGS. 43 and 44 ), but without operation of the recirculation pump P 3  and the plasma pump P 5 , as shown in  FIG. 47 . By preventing operation of the recirculation pump P 3  and the plasma pump P 5 , fluid will only exit the centrifugal separation chamber  36  via line L 5  (i.e., the red blood cell outlet). By such a configuration, the thickness of the red blood cell layer within the centrifugal separation chamber  36  will decrease. 
     At the end of the MNC transfer phase, the centrifugal separation chamber  36  is substantially entirely filled with packed red blood cells (in order to push the mononuclear cell-containing layer out of the centrifugal separation chamber  36 ). Rather than decreasing the thickness of the red blood cell layer to the level that is typically preferred during separation (e.g., in the range of approximately 50-75% of the total fluid thickness of the centrifugal separation chamber  36 , as in  FIG. 18 ), the red blood cell layer is instead brought to a lower thickness (as in  FIG. 20 ) in order to cause platelet-poor plasma instead of platelet-rich plasma to exit the centrifugal separation chamber  36  via line L 10  (i.e., the plasma outlet). The exact thickness of the red blood cell layer may vary without departing from the scope of the present disclosure, but it may be experimentally determined as the thickness at which platelet-poor plasma (instead of platelet-rich plasma) will tend to exit the centrifugal separation chamber  36  via line L 10  (i.e., the plasma outlet). In one example, the thickness of the red blood cell layer is reduced to a level that is less than half of the typically preferred thickness of the red blood cell layer during separation. In another example, the thickness of the red blood cell layer is reduced to a level (e.g., approximately 20% or less of the total fluid thickness of the centrifugal separation chamber  36 ) that is approximately one-third of the thickness of the red blood cell layer that is typically preferred during separation (e.g., approximately 60% of the total fluid thickness of the centrifugal separation chamber  36 ). 
     When the thickness of the red blood cell layer within the centrifugal separation chamber  36  has been reduced to a low enough level so as to produce platelet-poor plasma instead of platelet-rich plasma, the plasma pump P 5  is restarted (as shown in  FIG. 48 ). The platelet-poor plasma exiting the centrifugal separation chamber  36  via line L 10  clears the packed red blood cells remaining in lines L 10  and L 12  at the end of the MNC transfer phase. The platelet-poor plasma pushes the packed red blood cells from lines L 10  and L 12  to a recipient (e.g., the blood source) via lines L 13 , L 18 , and L 9 . 
     Once lines L 10  and L 12  are clear of packed red blood cells (which may be determined, for example, by a time delay after the centrifugal separator sensor M 1  detects platelet-poor plasma flowing through line L 10 ), the recirculation pump P 3  is restarted, the valve V 6  associated with valve station C 6  closes (to prevent further platelet-poor plasma from flowing through line L 13 ), and the valve V 7  associated with valve station C 7  opens (as shown in  FIG. 49 ). This causes the platelet-poor plasma exiting the centrifugal separation chamber  36  via line L 10  to flow through lines L 12 , L 14 , and L 16 , which pushes the mononuclear cells and T-cells in lines L 14  and L 16  (which were left there at the end of the MNC transfer phase) into the MNC collection container F 5 . This ensures complete collection of the mononuclear cells and T-cells, while minimizing the number of platelets transferred to the MNC collection container F 5  (compared to the number of platelets that would end up in the MNC collection container F 5  if platelet-rich plasma were instead used to flush the mononuclear cells and T-cells into the MNC collection container F 5 ). This phase can also be executed at the end of collection to ensure that the MNC product in the MNC collection container F 5  has the proper storage volume. 
     Restarting the recirculation pump P 3  begins to aid in the reestablishment of steady state separation (by increasing the separation efficiency of platelets from red blood cells and by increasing the thickness of the red blood cell layer within the centrifugal separation chamber  36 ) if an additional amount of mononuclear cells and T-cells is to be collected (by transitioning back into an MNC collection phase and repeating the foregoing procedure). The centrifugal separator sensor M 1  may be used to determine when platelet-rich plasma (instead of platelet-poor plasma) begins exiting the centrifugal separation chamber  36  via line L 10 , at which point the plasma flush phase transitions to an MNC collection phase and the procedure is repeated. The observed thickness of the red blood cell layer within the centrifugal separation chamber  36  may also be a factor in determining when to transition from the plasma flush phase to an MNC collection phase. 
     It should be noted that platelet-poor plasma created in the centrifugal separation chamber  36  during reestablishment of separation is used to flush mononuclear cells and T-cells from lines L 14  and L 16  into the MNC collection container F 5 . This is in contrast to conventional approaches, in which previously collected platelet-poor plasma is instead used to flush mononuclear cells into a collection container. The approach described herein may be advantageous to the extent that a platelet-poor plasma collection container is not required, which may reduce the number of components of the fluid flow circuit  12  and its complexity. Additionally, it is not necessary to execute a platelet-poor plasma collection phase. Furthermore, following one MNC collection cycle, separation must be reestablished in both the conventional procedure and the procedure described herein. By creating and using platelet-poor plasma during a phase that must occur regardless of the approach taken, the time required to complete the procedure may be reduced. 
     III. Subsequent T-Cell Processing 
     Following collection, the MNC product may be subjected to further processing, including electroporation-based treatment, such as CAR T-cell therapy. This may be carried out using a standalone, multifunctional device configured to execute the various steps of an electroporation-based treatment (including addition of DNA, electroporation, and cell washing), as is shown in  FIGS. 50 and 51 . Alternatively, this may be carried out using a dedicated electroporation device, which is configured only for electroporation of T-cells, with the blood separation device  10  executing the other steps of the electroporation-based treatment, as shown in  FIGS. 52-58 . 
     In either case, it will be seen that the entire process of MNC collection and subsequent processing is completed using a single, closed fluid flow circuit  12  and without disconnecting the source (e.g., a patient) from the fluid flow circuit  12  (i.e., as a “bedside” procedure). This is in contrast to a conventional approach, in which apheresis and electroporation-based processing (such as CAR T-cell therapy) take place in separate locations, with the source/patient being disconnected from an MNC product-containing fluid flow circuit during the electroporation-based treatment. It should be understood that these advantages may be realized regardless of the manner in which the MNC product is collected and is not limited to an MNC product that is separated via centrifugation or the particular process described herein. For example, some other (non-centrifuge) separation device may be used to separate the MNC product from blood prior to executing one of the electroporation-based procedures to be described. 
     A. Standalone, Multifunctional Device 
       FIGS. 50 and 51  show an MNC product being conveyed through a standalone, multifunctional device  118  ( FIG. 50 ) and then reinfused to the blood source ( FIG. 51 ). The exact configuration of the device  118  may vary without departing from the scope of the present disclosure, but it is configured to perform the various steps of an electroporation-based procedure (e.g., CAR T-cell therapy). This may include addition of DNA to the MNC product, electroporation of the MNC product (to open pores in a cell membrane of a T-cell, which allows the DNA to enter and modify the genome of the T-cell), and cell washing. 
     The manner in which the fluid flow circuit  12  is fluidly connected to the device  118  may vary according to the particular configuration of the device  118 . For example, as shown in  FIGS. 50 and 51 , a line or tubing or conduit of the fluid flow circuit  12  may be configured to be connected to the device  118  as an inlet, with at least a portion of the MNC product flowing into the device  118  via the inlet. Another line or tubing or conduit of the fluid flow circuit  12  may be configured to be connected to the device  118  as an outlet, with the modified MNC product exiting the device  118  via the outlet. In other embodiments, the fluid flow circuit  12  may be configured as a closed system, with the fluid flow circuit  12  including a portion configured to be placed into, mounted onto, or otherwise associated with the device  118  (e.g., including one or more containers or vessels configured to be associated with the device  118 ), rather than a plurality of lines or tubes or conduits of the fluid flow circuit  12  being connected to the device  118 . 
     1. Processing by Standalone, Multi-Functional Device 
     Regardless of the particular configuration of the standalone, multi-functional device  118 , the MNC product is transferred to it from the MNC collection container F 5  by operation of the transfer pump P 4  ( FIG. 50 ). The valve V 7  associated with valve station C 7  is opened (if not already open), while the valve V 6  associated with valve station C 6  is closed (if not already closed). The plasma pump P 5  is inactive, thus causing the transfer pump P 4  to pull the MNC product out of the MNC collection container F 5  via line L 16 , with the MNC product moving from line L 16  toward the transfer pump P 4  via line L 15 . 
     Line L 15  splits into lines L 19  and L 20  downstream of the transfer pump P 4 . Line L 19  leads into the standalone, multi-functional device  118 , while line L 20  leads through the sensor station S 4  associated with pressure sensor A 4  and into the spinning membrane separator  26 . The waste pump P 6  downstream of the spinning membrane separator  26  is inactive, along with the valve V 8  associated with valve station C 8  being closed, which causes the MNC product in line L 15  to move through line L 19  into the device  118 , rather than flowing through line L 20 . 
     The MNC product passes through the device  118 , where it is variously processed to edit the genomes of the T-cells. The processing carried out by the device  118  may include (without being limited to) the addition of DNA, cell washing, and electroporation (in various orders). The modified MNC product exits the device  118  via line L 21 . The valve V 9  associated with valve station C 9  is open, while the valve V 5  associated with valve station C 5  is closed, which directs the modified MNC product through line L 22  instead of through line L 17 . Line  22  splits into lines L 23  and L 24 . The valve V 8  associated with valve station C 8  is closed, thus preventing flow through line L 23 , while directing the modified MNC product through line L 24  and into an in-process container F 6 . 
     In an alternative embodiment, rather than conveying the modified MNC product from the device  118  into the in-process container F 6 , the modified MNC product may instead be conveyed from the device  118  to the source/patient via the fluid flow circuit  12 . 
     2. Reinfusion 
     With the modified MNC product in the in-process container F 6 , the transfer pump P 4  is deactivated and the valves V 7  and V 9  associated with valve stations C 7  and C 9  (respectively) are closed ( FIG. 51 ). The valves V 5  and V 11  associated with valve station C 5  and C 11  (respectively) are opened, which allows the modified MNC product to flow out of the in-process container F 6  via line L 24  via gravity and through lines L 22  and L 17 . The modified MNC product continues flowing (via gravity) through lines L 18  and L 9 , to be reinfused to the blood source/patient. The modified MNC product may be retained in the in-process container F 6  for a holding time prior to reinfusion. 
     B. Dedicated Electroporation Device without Cell Washing 
       FIGS. 52-58  show an MNC product being conveyed through a dedicated electroporation device  120  and then reinfused to the blood source. In contrast to the standalone, multifunctional device  118  of  FIGS. 50 and 51 , the device  120  of  FIGS. 52-58  is configured solely for electroporation, while the other steps of an electroporation-based procedure are executed elsewhere (as will be described). The exact configuration of the device  120  may vary without departing from the scope of the present disclosure. 
     The manner in which the fluid flow circuit  12  is fluidly connected to the device  120  may vary according to the particular configuration of the device  120 . For example, as shown in  FIGS. 52-58 , a line or tubing or conduit of the fluid flow circuit  12  may be configured to be connected to the device  120  as an inlet, with at least a portion of the MNC product flowing into the device  120  via the inlet. Another line or tubing or conduit of the fluid flow circuit  12  may be configured to be connected to the device  120  as an outlet, with the modified MNC product exiting the device  120  via the outlet. In other embodiments, the fluid flow circuit  12  may be configured as a closed system, with the fluid flow circuit  12  including a portion configured to be placed into, mounted onto, or otherwise associated with the device  120  (e.g., including one or more containers or vessels configured to be associated with the device  120 ), rather than a plurality of lines or tubes or conduits of the fluid flow circuit  12  being connected to the device  120 . 
     The processing of the T-cell lymphocytes may include or omit washing of the MNC product, with cell washing (if any) taking place before and/or after the electroporation stage. An electroporation-based procedure omitting cell washing will be described first, followed by exemplary procedures including one or more cell washing stages. 
     1. DNA Addition 
     According to an exemplary procedure in which cell washing is omitted, the DNA material required to edit the genome of the T-cells of the MNC product is first added to the MNC product in the MNC collection container F 5 , as in  FIG. 52 . The nature of the DNA material may vary depending on the desired configuration of the T-cells to be modified. The DNA material may be added to the MNC collection container F 5  according to any suitable approach (e.g., being injected via a port of the MNC collection container F 5  either automatically under the direction of the controller  18  or manually) or may be initially provided in the MNC collection container F 5  prior to association of the fluid flow circuit  12  to the blood separation device  10 . In one embodiment, the MNC product and the DNA material are allowed to remain within the MNC collection container F 5  for a holding time before electroporation begins. 
     2. Electroporation 
     The MNC product and DNA material are transferred to the dedicated electroporation device  120  from the MNC collection container F 5  by operation of the transfer pump P 4  ( FIG. 53 ). The valve V 7  associated with valve station C 7  is opened (if not already open), while the valve V 6  associated with valve station C 6  is closed (if not already closed). The plasma pump P 5  is inactive, thus causing the transfer pump P 4  to pull the MNC product and DNA material out of the MNC collection container F 5  via line L 16 , with the MNC product and DNA material moving from line L 16  toward the transfer pump P 4  via line L 15 . The waste pump P 6  downstream of the spinning membrane separator  26  is inactive, along with the valve V 8  associated with valve station C 8  being closed, which causes the MNC product and DNA material in line L 15  to move through line L 19  into the device  120 , rather than flowing through line L 20 . 
     The MNC product and DNA material pass through the device  120 , where it is subjected to electroporation, which allows for the DNA material to enter into and modify the genome of the T-cells. 
     The modified MNC product exits the device  120  via line L 21 . The valve V 9  associated with valve station C 9  is open, while the valve V 5  associated with valve station C 5  is closed, which directs the modified MNC product through line L 22  instead of through line L 17 . The valve V 8  associated with valve station C 8  is closed, thus preventing flow through line L 23 , while directing the modified MNC product through line L 24  and into the in-process container F 6 . 
     In an alternative embodiment, rather than conveying the modified MNC product from the device  120  into the in-process container F 6 , the modified MNC product may instead be conveyed from the device  120  to the source/patient via the fluid flow circuit  12 . 
     3. Reinfusion 
     With the modified MNC product in the in-process container F 6 , the transfer pump P 4  is deactivated and the valves V 7  and V 9  associated with valve stations C 7  and C 9  (respectively) are closed ( FIG. 54 ). The valves V 5  and V 11  associated with valve stations C 5  and C 11  (respectively) are opened, which allows the modified MNC product to flow out of the in-process container F 6  via line L 24  via gravity and through lines L 22  and L 17 . The modified MNC product continues flowing (via gravity) through lines L 18  and L 9 , to be reinfused to the blood source/patient. The modified MNC product may be retained in the in-process container F 6  for a holding time prior to reinfusion. 
     C. Cell Washing Prior to Electroporation 
     While cell washing may be omitted, there are situations in which it may be advantageous to wash the MNC product, before and/or after electroporation. Washing the MNC product prior to electroporation may be useful for reducing the plasma volume of the MNC product, replacing one cell suspension fluid (e.g., plasma) with another (e.g., a solution that enables specific actions carried out during the electroporation-based procedure), and/or removing residual cells (e.g., platelets), for example. Thus, cell washing before electroporation may be advantageous if it is deemed necessary or desirable to achieve one or more of the preceding results. 
     1. Cell Washing 
       FIG. 55  shows an approach to washing the MNC product prior to electroporation. The MNC product is pulled out of the MNC collection container F 5  by operation of the transfer pump P 4 . The valve V 7  associated with valve station C 7  is opened (if not already open), while the valve V 6  associated with valve station C 6  is closed (if not already closed). The plasma pump P 5  is inactive, thus causing the transfer pump P 4  to pull the MNC product out of the MNC collection container F 5  via line L 16 , with the MNC product moving from line L 16  toward the transfer pump P 4  via line L 15 . The waste pump P 6  downstream of the spinning membrane separator  26  is operative, along with the valve V 8  associated with valve station C 8  being open and the valve V 9  associated with valve station C 9  being closed, which causes the MNC product in line L 15  to move through line L 20  into the spinning membrane separator  26 , rather than flowing through line L 19  into the dedicated electroporation device  120 . 
     The MNC product passes into the spinning membrane separator  26 , which separates the MNCs and T-cells from a waste product. As described above, the nature of the waste product may vary depending on the configuration of the spinning membrane separator  26 , with smaller pores filtering out supernatant and larger pores separating out supernatant and residual cell types (such as platelets and smaller red blood cells), depending on the desired composition of the washed MNC product. 
     The MNCs and T-cells exit the spinning membrane separator  26  via line L 23 , while the waste product exits the spinning membrane separator  26  via line L 25  and flows into a second waste container F 7 . The waste product may be monitored by the spinner outlet sensor M 2  to detect its optical characteristics for quality purposes (e.g., monitoring for cell loss and/or hemolysis). 
     The valve V 8  associated with valve station C 8  is open, while the valves V 5  and V 9  associated with valve stations C 5  and C 9  (respectively) are closed, thus directing the MNCs and T-cells into the in-process container F 6  via lines L 23  and L 24  as a washed MNC product. 
     2. DNA Addition 
     The DNA material required to edit the genome of the T-cells of the washed MNC product is added to the washed MNC product in the in-process container F 6 , as in  FIG. 56 . The nature of the DNA material may vary depending on the desired configuration of the T-cells to be modified. The DNA material may be added to the in-process container F 6  according to any suitable approach (e.g., being injected via a port of the in-process container F 6 ) or may be initially provided in the in-process container F 6  prior to association of the fluid flow circuit  12  to the blood separation device  10 . In one embodiment, the washed MNC product and the DNA material are allowed to remain within the in-process container F 6  for a holding time before electroporation begins. 
     3. Electroporation 
     As shown in  FIG. 57 , the washed MNC product and DNA material are transferred to the dedicated electroporation device  120  from the in-process container F 6  by the transfer pump P 4  operating in reverse of its direction during the cell washing stage of  FIG. 55 . The valve V 9  associated with valve station C 9  is opened, while the valves V 5  and V 8  associated with valve stations C 5  and C 8  (respectively) remain closed. This causes the washed MNC product and DNA material to be pulled out of the in-process container F 6  via line L 24 , through lines L 22  and L 21 , and into the dedicated electroporation device  120 . 
     The washed MNC product and DNA material pass through the device  120 , where it is subjected to electroporation, which allows for the DNA material to enter into and modify the genome of the T-cells. It will be seen that the flow of fluid through the device  120  is opposite in the electroporation stages of  FIG. 53  (in which the MNC product is not washed) and  FIG. 57  (in which the MNC product is washed prior to electroporation). In one embodiment, the device  120  is direction independent, such that fluid flowing through it in either direction may be subjected to electroporation. Alternatively, if the device  120  is configured to be direction dependent (i.e., fluid will only be subjected to electroporation upon entering through a designated inlet), different fluid circuits (with opposite orientations of the device  120 ) may be used depending on whether the MNC product is to be washed before electroporation or not. 
     The modified MNC product exits the device  120  via line L 19 . The waste pump P 6  downstream of the spinning membrane separator  26  is inactive, along with the plasma pump P 5 . The valves V 6  and V 8  associated with valve stations C 6  and C 8  (respectively) are closed, while the valve V 7  associated with valve station C 7  is open, which causes the modified MNC product to flow through lines L 15  and L 16  and into the MNC collection container F 5 . 
     In an alternative embodiment, rather than conveying the modified MNC product from the device  120  into the MNC collection container F 5 , the modified MNC product may instead be conveyed from the device  120  to the source/patient via the fluid flow circuit  12 . 
     4. Reinfusion 
     With the modified MNC product in the MNC collection container F 5 , the transfer pump P 4  is deactivated and the valves V 6  and V 11  associated with valve stations C 6  and C 11  (respectively) are opened ( FIG. 58 ). This allows the modified MNC product to flow out of the MNC collection container F 5  via line L 16  via gravity and through lines L 14  and L 13 . The modified MNC product continues flowing (via gravity) through lines L 18  and L 9 , to be reinfused to the blood source/patient. The modified MNC product may be retained in the MNC collection container F 5  for a holding time prior to reinfusion. 
     D. Cell Washing Prior to and Following Electroporation 
     Rather than only washing the MNC product prior to electroporation, it is also within the scope of the present disclosure for the MNC product to be washed prior to electroporation and then again after electroporation. Washing the MNC product following electroporation may be useful for removing any solutions used during electroporation of the MNC product that are not suitable for reinfusion and/or reducing the volume or increasing the concentration of the modified MNC product, for example. Thus, cell washing following electroporation may be advantageous if it is deemed necessary or desirable to achieve one or more of the preceding results (in addition to the results achieved by washing the MNC product before electroporation). 
     1. Pre-Electroporation Cell Washing 
     The MNC product may be washed prior to electroporation by the approach shown in  FIG. 55  and described above with respect to the procedure in which the MNC product is only washed once. Per the foregoing description, the nature of the waste product filtered from the MNCs and T-cells may vary depending on the configuration of the spinning membrane separator  26 . 
     2. DNA Addition 
     Following washing, DNA material may be added to the washed MNC product by the approach shown in  FIG. 56  and described above with respect to the procedure in which the MNC product is only washed once. Per the foregoing description, the washed MNC product and DNA material may be retained in the in-process container F 6  for a holding time prior to the electroporation stage. 
     3. Electroporation 
     The washed MNC product and DNA material may be subject to electroporation by the approach shown in  FIG. 57  and described above with respect to the procedure in which the MNC product is only washed once. The washed, modified MNC product may be retained in the MNC collection container F 5  for a holding time prior to the second washing stage. 
     4. Post-Electroporation Cell Washing 
     The washed and modified MNC product flows into the MNC collection container F 5  following the electroporation stage. The washed and modified MNC product may then be washed again according to the same approach used for the pre-electroporation washing (i.e., as shown in  FIG. 55 ), with the modified, twice-washed MNC product flowing into the in-process container F 6 . Washing the modified MNC product may be advantageous in order to remove contaminants, such as suspension media or leftover DNA material that did not enter into a T-cell during the electroporation stage. The modified, twice-washed MNC product may be retained in the in-process container F 6  for a holding time prior to reinfusion. 
     5. Reinfusion 
     Finally, the modified, twice-washed MNC product may be reinfused to the blood source/patient by the approach shown in  FIG. 54  and described above with respect to the procedure in which the MNC product is not washed. 
     It should be understood that the electroporation-based treatments described herein are merely exemplary and that other electroporation-based treatments are encompassed by the present disclosure. For example, rather than only washing the MNC product prior to electroporation or both before and after electroporation, it is also possible to only wash the MNC product after electroporation, without also washing the MNC product prior to the electroporation stage (e.g., if the benefits of pre-electroporation washing are not required). It should also be understood that cell washing may be carried out in combination with the standalone, multi-functional device  118  of  FIGS. 50 and 51 , particularly if the device  118  is not configured to wash the MNC product. 
     Aspects 
     Aspect 1. A fluid processing system, comprising: a separation device; an electroporation device; a pump assembly including a plurality of pumps; and a controller configured to actuate the pump assembly to convey blood from a blood source into the separation device, actuate the separation device to separate a mononuclear cell product from the blood, actuate the pump assembly to convey at least a portion of the mononuclear cell product into the electroporation device to modify a genome of at least one of the cells of the mononuclear cell product, and actuate the pump assembly to convey at least a portion of the modified mononuclear cell product to the blood source. 
     Aspect 2. The fluid processing system of Aspect 1, wherein the separation device comprises a centrifuge. 
     Aspect 3. The fluid processing system of any one of the preceding Aspects, further comprising a second separation device configured to be actuated by the controller to wash the mononuclear cell product and/or the modified mononuclear cell product. 
     Aspect 4. The fluid processing system of Aspect 3, wherein the controller is configured to actuate the second separation device to wash the mononuclear cell product prior to actuating the pump assembly to convey said at least a portion of the mononuclear cell product into the electroporation device. 
     Aspect 5. The fluid processing system of Aspect 3, wherein the controller is configured to actuate the second separation device to wash the modified mononuclear cell product after actuating the pump assembly to convey said at least a portion of the mononuclear cell product into the electroporation device. 
     Aspect 6. The fluid processing system of Aspect 3, wherein the controller is configured to actuate the second separation device to wash the mononuclear cell product prior to actuating the pump assembly to convey said at least a portion of the mononuclear cell product into the electroporation device and to actuate the second separation device to wash the modified mononuclear cell product after actuating the pump assembly to convey said at least a portion of the mononuclear cell product into the electroporation device. 
     Aspect 7. The fluid processing system of any one of the preceding Aspects, wherein the controller is configured to actuate the pump assembly to collect and retain the modified mononuclear cell product for a holding time prior to conveying said at least a portion of the modified mononuclear cell product to the blood source. 
     Aspect 8. The fluid processing system of any one of Aspects 1-4, wherein the controller is configured to actuate the pump assembly to convey said at least a portion of the modified mononuclear cell product to the blood source without first collecting and retaining the modified cell product for a holding time. 
     Aspect 9. The fluid processing system of any one of the preceding Aspects, wherein the electroporation device is configured to execute multiple steps of an electroporation-based procedure, including addition of DNA material to the mononuclear cell product and electroporation. 
     Aspect 10. The fluid processing system of any one of Aspects 1-8, wherein the electroporation device is configured to subject the mononuclear cell product to electroporation, but not configured to add DNA material to the mononuclear cell product. 
     Aspect 11. A method for processing blood, comprising: drawing blood from a blood source into a fluid flow circuit; separating a mononuclear cell product from the blood; conveying at least a portion of the mononuclear cell product into an electroporation device without disconnecting the blood source from the fluid flow circuit to modify a genome of at least one of the cells of the mononuclear cell product; and returning at least a portion of the modified mononuclear cell product to the blood source. 
     Aspect 12. The method of Aspect 11, wherein the mononuclear cell product is separated from the blood by centrifugation. 
     Aspect 13. The method of any one of Aspects 11-12, further comprising washing the mononuclear cell product prior to said at least a portion of the mononuclear cell product being conveyed into the electroporation device. 
     Aspect 14. The method of any one of Aspects 11-12, further comprising washing the modified mononuclear cell product after said at least a portion of the mononuclear cell product is conveyed into the electroporation device. 
     Aspect 15. The method of any one of Aspects 11-12, further comprising washing the mononuclear cell product prior to said at least a portion of the mononuclear cell product being conveyed into the electroporation device, and washing the modified mononuclear cell product after actuating the pump assembly to convey said at least a portion of the mononuclear cell product into the electroporation device. 
     Aspect 16. The method of any one of Aspects 11-15, further comprising collecting and retaining the modified mononuclear cell product for a holding time prior to returning said at least a portion of the modified mononuclear cell product to the blood source. 
     Aspect 17. The method of any one of Aspects 11-13, wherein said at least a portion of the modified mononuclear cell product is returned to the blood source without first collecting and retaining the modified cell product for a holding time. 
     Aspect 18. The method of any one of Aspects 11-17, wherein the electroporation device is configured to execute multiple steps of an electroporation-based procedure, including addition of DNA material to the mononuclear cell product and electroporation. 
     Aspect 19. The method of any one of Aspects 11-17, further comprising manually adding DNA material to the mononuclear cell product prior to said at least a portion of the mononuclear cell product being conveyed into the electroporation device. 
     Aspect 20. The method of any one of Aspects 11-17, further comprising automatically adding DNA material to the mononuclear cell product prior to said at least a portion of the mononuclear cell product being conveyed into the electroporation device. 
     It will be understood that the embodiments and examples described above are illustrative of some of the applications of the principles of the present subject matter. Numerous modifications may be made by those skilled in the art without departing from the spirit and scope of the claimed subject matter, including those combinations of features that are individually disclosed or claimed herein. For these reasons, the scope hereof is not limited to the above description but is as set forth in the following claims, and it is understood that claims may be directed to the features hereof, including as combinations of features that are individually disclosed or claimed herein.