GRAVITY FLOW MICRO-PHYSIOLOGICAL ARTICLE AND DETERMINING A PHYSIOLOGICAL RESPONSE TO A DRUG

A gravity flow micro-physiological article determines a physiological response to a drug and includes: supply chambers; a mixing chamber; and a liquid divider, wherein the divider divides fluid under gravitational force so that individual portions of the fluid independently include metabolites in a proportionate amount as physically determined by the liquid divider.

BRIEF DESCRIPTION

Disclosed is a gravity flow micro-physiological article for determining a physiological response to a drug, the gravity flow micro-physiological article comprising: a substrate; a first supply chamber disposed on the substrate and that provides a first supply fluid flow; a second supply chamber disposed on the substrate and that provides a second supply fluid flow, such that the first supply fluid flow from the first supply chamber is parallel to the second supply fluid flow from the second supply chamber; a mixing chamber in fluid communication with the first supply chamber and the second supply chamber and that: receives the first supply fluid flow from the first supply chamber; receives the second supply fluid flow from the second supply chamber; and combines the first supply fluid flow and the second supply fluid flow to form a combined fluid flow; a liquid divider in fluid communication with the mixing chamber and that: receives the combined fluid flow from the mixing chamber; and divides the combined fluid flow into a first divided fluid flow and a second divided fluid flow, wherein the liquid divider is in fluid communication with the first supply chamber and the second supply chamber such that: the first supply chamber receives the first divided fluid flow from the liquid divider; and the second supply chamber receives the second divided fluid flow from the liquid divider.

Disclosed is a process for determining a physiological response to a drug with a gravity flow micro-physiological article, the process comprising: disposing a first biological cell in a first supply chamber of the gravity flow micro-physiological article; disposing a second biological cell in a second supply chamber of the gravity flow micro-physiological article; disposing a blood surrogate in a liquid divider of the gravity flow micro-physiological article, the blood surrogate comprising the drug; subjecting the gravity flow micro-physiological article to movement to divide the blood surrogate into a first divided fluid flow and a second divided fluid flow of the gravity flow micro-physiological article, wherein the first divided fluid flow and the second divided fluid flow independently comprise a portion of the blood surrogate in a proportionate amount as physically determined by the divider of the gravity flow micro-physiological article; communicating the first divided fluid flow to the first supply chamber; receiving, by the first supply chamber, the first divided fluid flow from a first return fluid chamber of the gravity flow micro-physiological article; communicating the second divided fluid flow to the second supply chamber; receiving, by the second supply chamber, the second divided fluid flow from a second return fluid chamber of the gravity flow micro-physiological article; contacting; in the first supply chamber, the first biological cell with the drug in the first divided fluid flow; producing a first metabolite from the first biological cell in response to contact with the drug in the first divided fluid flow; contacting, in the second supply chamber, the second biological cell with the drug in the second divided fluid flow; producing a second metabolite from the second biological cell in response to contact with the drug in the second divided fluid flow; producing, by the first supply chamber, a first supply fluid flow that comprises the first metabolite; producing, by the second supply chamber, a second supply fluid flow that comprises the second metabolite; communicating, in parallel to a mixing chamber, the first supply fluid flow from the first supply chamber and the second supply fluid flow from the second supply chamber; receiving, by the mixing chamber, in parallel, the first supply fluid flow and the second supply fluid flow; combining, by the mixing chamber, the first supply fluid flow and the second supply fluid flow to produce a combined fluid flow that comprises the first metabolite and the second metabolite; communicating, from the mixing chamber, the combined fluid flow; receiving, by the liquid divider, the combined fluid flow from the mixing chamber; and dividing, under gravitational force, the combined fluid flow into the first divided fluid flow and the second divided fluid flow, wherein the first divided fluid flow and the second divided fluid flow independently comprise of the first metabolite and the second metabolite in a proportionate amount as physically determined by the divider to determine independently the physiological response of the first biological cell and the second biological cell to the drug.

DETAILED DESCRIPTION

It has been discovered that gravity flow micro-physiological article200is a microphysiological system that operates as an open microfluidic system. Fluidic flow is achieved via gravity, and physiologic fluid residence times are achieved by placing gravity flow micro-physiological article200at various angles, e.g., by a rotating or rocking gravity flow micro-physiological article200. Gravity flow micro-physiological article200can include near-physiologic amounts of a blood surrogate.

Gravity flow micro-physiological article200overcomes technological impairments with conventional microphysiological systems. Exemplary problems with conventional microphysiological systems that are overcome by gravity flow micro-physiological article200include insensitivity of conventional systems to toxic metabolites in biological fluid (e.g., a blood surrogate) due to dilution of toxic metabolites in an excess volume of fluid carrier; unreliability of conventional microphysiological systems with respect to tissue death caused by sample leakage by the conventional microphysiological systems; uptake of air bubbles in a blood surrogate in a flow of the blood surrogate in the conventional microphysiological systems; and failure of conventional microphysiological systems because active components (e.g., a pump, valve, and the like) of the conventional microphysiological systems that cease to function.

Gravity flow micro-physiological article200determines a physiological response to a drug. In an embodiment, with reference toFIG. 1,FIG. 2,FIG. 3,FIG. 4;FIG. 5,FIG. 6,FIG. 7;FIG. 8,FIG. 9, andFIG. 10, gravity flow micro-physiological article200includes: a substrate201; a first supply chamber202.1disposed on the substrate201and that provides a first supply fluid flow206.1; a second supply chamber202.1disposed on the substrate201and that provides a second supply fluid flow206.2, such that the first supply fluid flow206.1from the first supply chamber202.1is parallel to the second supply fluid flow206.2from the second supply chamber202.2; a mixing chamber203in fluid communication with the first supply chamber202.1and the second supply chamber202.2and that: receives the first supply fluid flow206.1from the first supply chamber202.1; receives the second supply fluid flow206.2from the second supply chamber202.2; and combines the first supply fluid flow206.1and the second supply fluid flow206.2to form a combined fluid flow207; a liquid divider205in fluid communication with the mixing chamber203and that: receives the combined fluid flow207from the mixing chamber203; and divides the combined fluid flow207into a first divided fluid flow211.1and a second divided fluid flow211.2; wherein the liquid divider205is in fluid communication with the first supply chamber202.1and the second supply chamber202.2such that: the first supply chamber202.1receives the first divided fluid flow211.1from the liquid divider205; and the second supply chamber202.1receives the second divided fluid flow211.2from the liquid divider205.

In an embodiment, the liquid divider205includes a divider209that partitions the liquid divider205into a plurality of return fluid chambers208. In an embodiment, the return fluid chambers208comprises a first return fluid chamber208.1, a second return fluid chamber208.2, a third return fluid chamber208.3, . . . , and an n-th return fluid chamber208.n, wherein n is an integer that can be selected based on a number of supply chambers202disposed on the substrate201of the gravity flow micro-physiological article200.

In an embodiment; gravity flow micro-physiological article200includes a plurality of flow channels204that fluidically interconnects the supply chamber202, the mixing chamber203, and the liquid divider205and provides fluid flow between the supply chamber202, the mixing chamber203, and the liquid divider205.

In an embodiment, the first supply chamber202.1receives a first biological cell213.1; the second supply chamber202.2receives a second biological cell213.2; and the liquid divider205receives a blood surrogate214comprising the drug. In an embodiment, the gravity flow micro-physiological article200divides the blood surrogate214into a first divided fluid flow211.1and a second divided fluid flow211.2in response to the gravity flow micro-physiological article200being subjected to movement, wherein the first divided fluid flow211.1and the second divided fluid flow211.2independently comprise a portion of the blood surrogate214in a proportionate amount as physically determined by the divider209. In an embodiment, the gravity flow micro-physiological article200communicates the first divided fluid flow211.1to the first supply chamber202.1; the first supply chamber202.1receives the first divided fluid flow211.1from the first return fluid chamber208.1; the gravity flow micro-physiological article200communicates the second divided fluid flow211.2to the second supply chamber202.2; and the second supply chamber202.2receives the second divided fluid flow211.2from the second return fluid chamber208.2of the gravity flow micro-physiological article200. In an embodiment, in the first supply chamber202.1, the first biological cell213.1contacts the drug in the first divided fluid flow211.1, so that a first metabolite215.1is produced by the first biological cell213.1in response to contact with the drug in the first divided fluid flow211.1; and, in the second supply chamber202.2, the second biological cell213.2contacts the drug in the second divided fluid flow211.2, so that a second metabolite215.2is produced by the second biological cell213.2in response to contact with the drug in the second divided fluid flow211.2. In an embodiment, the first supply chamber202.1produces a first supply fluid flow206.1that comprises the first metabolite215.1; the second supply chamber202.2produces a second supply fluid flow206.2that comprises the second metabolite215.2; and the first supply fluid flow206.1from the first supply chamber202.1and the second supply fluid flow206.2from the second supply chamber202.2are communicated in parallel to the mixing chamber203. In an embodiment, the mixing chamber203receives, in parallel, the first supply fluid flow206.1and the second supply fluid flow206.2; combines the first supply fluid flow206.1and the second supply fluid flow206.2; produces a combined fluid flow207that comprises the first metabolite215.1and the second metabolite215.2; and communicates the combined fluid flow207to the liquid divider205. In an embodiment, the liquid divider205receives the combined fluid flow207from the mixing chamber203; and divides, under gravitational force, the combined fluid flow207into the first divided fluid flow211.1and the second divided fluid flow211.2, such that the first divided fluid flow211.1and the second divided fluid flow211.2independently comprise the first metabolite215.1and the second metabolite215.2in a proportionate amount as physically determined by the divider209.

Gravity flow micro-physiological article200can be made in various ways. It should be appreciated that gravity flow micro-physiological article200includes a number of optical, electrical, or mechanical components, wherein such components can be interconnected and placed in communication (e.g., optical communication, electrical communication, mechanical communication, and the like) by physical, chemical, optical, or free-space interconnects. Elements of gravity flow micro-physiological article200can be formed from a polymer although other suitable materials, such ceramic, glass, or metal can be used. According to an embodiment, the elements of gravity flow micro-physiological article200are formed using 3D printing although the elements of gravity flow micro-physiological article200can be formed using other methods, such as injection molding or machining a stock material such as block of material that is subjected to removal of material such as by cutting, laser oblation, and the like. Accordingly, gravity flow micro-physiological article200can be made by additive or subtractive manufacturing. In an embodiment, elements of gravity flow micro-physiological article200are selectively etched to remove various different materials using different etchants and photolithographic masks and procedures. In some embodiments, various layers formed that are subjected to joining by bonding to form gravity flow micro-physiological article200.

Gravity flow micro-physiological article200has numerous advantageous and unexpected benefits and uses. In an embodiment, with reference toFIG. 11andFIG. 12, a process for determining a physiological response to a drug with gravity flow micro-physiological article200includes: disposing first biological cell213.1in a first supply chamber202.1of the gravity flow micro-physiological article200(step300); disposing second biological cell213.2in a second supply chamber202.2of the gravity flow micro-physiological article200(step301); disposing a blood surrogate214in a liquid divider205of the gravity flow micro-physiological article200, the blood surrogate214comprising the drug (step302); subjecting the gravity flow micro-physiological article200to movement to divide the blood surrogate214into a first divided fluid flow211.1and a second divided fluid flow211.2of the gravity flow micro-physiological article200(step303), wherein the first divided fluid flow211.1and the second divided fluid flow211.2independently include a portion of the blood surrogate214in a proportionate amount as physically determined by a divider209of the gravity flow micro-physiological article200; communicating the first divided fluid flow211.1to the first supply chamber202.1(step304); receiving, by the first supply chamber202.1, the first divided fluid flow211.1from a first return fluid chamber208.1of the gravity flow micro-physiological article200(step305); communicating the second divided fluid flow211.2to the second supply chamber202.2(step306); receiving, by the second supply chamber202.2, the second divided fluid flow211.2from a second return fluid chamber208.2of the gravity flow micro-physiological article200(step307); contacting, in the first supply chamber202.1, the first biological cell213.1with the drug in the first divided fluid flow211.1(step308); producing a first metabolite215.1from the first biological cell213.1in response to contact with the drug in the first divided fluid flow211.1(step309); contacting, in the second supply chamber202.2, the second biological cell213.2with the drug in the second divided fluid flow211.2(step310); producing a second metabolite215.2from the second biological cell213.2in response to contact with the drug in the second divided fluid flow211.2(step311); producing, by the first supply chamber202.1, a first supply fluid flow206.1that includes the first metabolite215.1(step312); producing, by the second supply chamber202.2, a second supply fluid flow206.2that includes the second metabolite215.2(step313); communicating, in parallel to a mixing chamber203, the first supply fluid flow206.1from the first supply chamber202.1and the second supply fluid flow206.2from the second supply chamber202.2(step314); receiving, by the mixing chamber203, in parallel, the first supply fluid flow206.1and the second supply fluid flow206.2(step315); combining, by the mixing chamber203, the first supply fluid flow206.1and the second supply fluid flow206.2to produce a combined fluid flow207that comprises the first metabolite215.1and the second metabolite215.2(step316); communicating, from the mixing chamber203, the combined fluid flow207(step317); receiving, by the liquid divider205, the combined fluid flow207from the mixing chamber203(step318); and dividing; under gravitational force, the combined fluid flow207into the first divided fluid flow211.1and the second divided fluid flow211.2(step319), wherein the first divided fluid flow211.1and the second divided fluid flow211.2independently include the first metabolite215.1and the second metabolite215.2in a proportionate amount as physically determined by the divider209to determine independently the physiological response of the first biological cell213.1and the second biological cell213.2to the drug.

In an embodiment, determining a physiological response to a drug further includes repeatedly iterating steps304to318. for a select number of times to determine independently the physiological response of the first biological cell213.1and the second biological cell213.2to the drug.

In an embodiment, the first cell and the second cell independently include a normal cell, diseased cell, or a combination of the foregoing types of cells. In an embodiment, the drug comprises a therapeutic drug. In an embodiment, the blood surrogate includes the drug.

Pharmacokinetics is the study of the action of pharmaceuticals and other biologically active compounds from the time they are introduced into the body until they are eliminated. The sequence of events for an oral drug can include absorption through the various mucosal surfaces, distribution via the blood stream to various tissues, biotransformation in the liver and other tissues, action at the target site, and elimination of drug or metabolites in urine or bile. Pharmacokinetics provides a rational means of approaching the metabolism of a compound in a biological system. Gravity flow micro-physiological article200can provide pharmokinetic data at the cellular level for such a drug.

A challenge encountered in drug, environmental, nutritional, consumer product safety, or toxicology studies involves extrapolation of metabolic data and risk assessment from in vitro cell culture assays to animals. Although some conclusions can be drawn with the application of appropriate pharmacokinetic principles, substantial limitations can exist. Conventional screening assays use cells under conditions that may involve uncontrolled factors. The circulatory flow, interaction with other tissues, and other parameters associated with a physiological response may include spurious results in data that are not a direct result from cellular metabolism but from other factors. While in vivo animal models can be used to perform pharmacokinetics (PK) or pharmacodynamics (PD) study, it significantly can increase the cost of the research, and the screening throughput is low. Beneficially, gravity flow micro-physiological article200fills a need for a platform under which cells can function in controlled conditions with a target drug in a selected blood surrogate. Accordingly, gravity flow micro-physiological article200can be used, e.g., for PK or PD studies, drug screening, development of a disease model of interest, and the like.

Gravity flow micro-physiological article200can be configured to mimic physiological conditions or provide a platform for investigating cellular response to a compound or composition in a target motif, e.g., a mammal cell (e.g., a human cell), other animal cell, an insect cell, or a plant cell. Gravity flow micro-physiological article200can receive one type of living cells, e.g., one type of tissue cells under certain chemical conditions. Cells from various organs or tissue can include epithelial cells, cardiac cells, liver cell types (e.g., hepatocytes, hepatic stellate cells. Kupffer cells, or liver sinusoidal endothelial cells), kidney cells (e.g., intestinal epithelium, enterocytes, Paneth cells, goblet cells, or neuroendocrine cells), lung airway smooth muscle cells, osteocytes, skin cell types (e.g., keratinocytes, melanocytes, or Langerhans cells), brain cells (e.g., nerve cells or glial cells), gametes, germ cells, endocrine cells, and the like.

In some embodiments, gravity flow micro-physiological article200can be configured to represent a functional microenvironment of an organ (e.g., a functional unit or section of an organ, or a tissue-capillary interface) or metabolic condition in which cells can encounter the drug in the blood surrogate. In such embodiments, two different cell types can be disposed in gravity flow micro-physiological article200. In some embodiments, living human cells can be cultured and transferred into gravity flow micro-physiological article200under a physiological condition that can correspond, e.g., to such a physiological condition in a human organ.

It should be appreciated that gravity flow micro-physiological article200provides an in vivo model for various applications, e.g., in analysis of drug efficacy, toxicity, or pharmacodynamics, or in studies of diseases or disorders. To this end, gravity flow micro-physiological article200can have various designs and configurations that can include fluidics due to movement (e.g., rotation, tilting, and the like) of gravity flow micro-physiological article200and the effect of gravity on the fluid compositions (e.g., blood surrogate, drugs, cells, and the like) disposed in the gravity flow micro-physiological article200for fluid movement of such fluids inside of gravity flow micro-physiological article200. Accordingly, gravity flow micro-physiological article200can mimic a physiological condition.

In an embodiment, a plurality (e.g., two or more) gravity flow micro-physiological articles200can be fluidically connected together when one or more other fluid connector members (e.g., devices, systems, or modules that can perform fluid transfer, filtration, signal detection, or imaging) are present between the gravity flow micro-physiological articles200. Here, gravity flow micro-physiological articles200can be fluidically connected, when the gravity flow micro-physiological articles200are indirectly connected, e.g., through a biosensor, a filter, or an analytical instrument (e.g., via tubing), such that a fluid exiting the previous gravity flow micro-physiological article200can be communicated to first flow through a biosensor, filter, or analytical instrument, e.g., for detection, analysis, or filtration of the fluid, before it enters a next gravity flow micro-physiological article200. A portion of the fluid can pass or flow from one gravity flow micro-physiological article200to another gravity flow micro-physiological article200. In an embodiment, a plurality of gravity flow micro-physiological articles200can be connected such that a fluid can pass or flow directly from one gravity flow micro-physiological article200to another gravity flow micro-physiological article200in an absence of intervening components. In such an embodiment, gravity flow micro-physiological articles200can be designed or integrated such that the outlet of one gravity flow micro-physiological article200and the inlet of another gravity flow micro-physiological article200share the same port.

Gravity flow micro-physiological article200determines a physiological response to a drug, a biological effect (e.g., toxicity, immune response, metabolic formation, kinetic rate, and the like) of a drug. The drug can include an active agent, and the blood surrogate can include, in addition to the drug, an appropriate medium for metabolic support of certain cells. Gravity flow micro-physiological article200can receive the blood surrogate so that cells can be held under conditions of a disease or disorder and subjected to various kinds or dosages of drugs to determine an optimal treatment regimen for the disease or disorder.

Exemplary active agents include proteins, peptides, antigens, antibodies or portions thereof, enzymes, nucleic acids, siRNA, shRNA, aptamers, small molecules, antibiotics, therapeutic agents, molecular toxins, nanomaterials, particulates, or a combination thereof. In some embodiments, gravity flow micro-physiological article200is used to evaluate active agents that are effective in treating a disease or disorder but that might be toxic at certain levels.

The blood surrogate also can include other compositional constituents such as saline, plasma, aerosols, environmental contaminants or pollutants (e.g., microorganisms, organic or inorganic contaminants present in food or water, or air pollutants), viruses, bacteria, and the like.

Elements of gravity flow micro-physiological article200can be various sizes. It is contemplated that elements of gravity flow micro-physiological article200can be have have various length, volumes, shapes, and sizes to effect fluid communication in an absence of interference with determining a physiological response to a drug.

Elements of gravity flow micro-physiological article200can be made of a material that is physically or chemically resilient in an environment in which gravity flow micro-physiological article200is disposed. Exemplary materials include a metal, ceramic, thermoplastic, glass, semiconductor, and the like. The elements of gravity flow micro-physiological article200can be made of the same or different material and can be monolithic in a single physical body or can be separate members that are physically joined.

Gravity flow micro-physiological article200includes substrate201and flow channel204, supply chamber202, and divider209disposed therein. The number and dimension of flow channel204, supply chamber202, and divider209can vary depending on the design, dimension, or function of gravity flow micro-physiological article200. In some embodiments, gravity flow micro-physiological article200includes a plurality of such structures (e.g., from two to ten or more). A design and optimum number or dimension of flow channel204, supply chamber202, and divider209can be selected for a certain application. For example, if assessment of reproducibility or comparison of two conditions is desirable, gravity flow micro-physiological article200can be constructed to include from two to five flow channels204, supply chambers202, and dividers209. This can provide for a number of read-outs per flow channel204, supply chamber202, and divider209, e.g., allowing assessment of reproducibility or for validation and implementation of the technology. For example, each supply chamber202can run a different condition (e.g., normal (healthy) cells vs. diseased cells, applying different dosages of the same drug, or applying different drugs at the same dosage to different cells).

The dimensions of flow channel204, supply chamber202, and divider209can each independently vary, e.g., depending on the function (e.g., as a conduit for fluid transfer or as a chamber for monitoring cellular response), flow conditions, cellular microenvironment to be simulated, or methods for detecting cellular response. Thus, the cross-sectional dimensions of flow channel204, supply chamber202, and divider209independently can be, e.g., from about 1 μm to about 10 cm, or from about 1 μm to about 0.5 cm. A volume of flow channel204, supply chamber202, and divider209independently can be, e.g., 10 nanoliters to 1 liter, specifically from 100 nL to 100 mL, and more specifically from 10 nL to 50 μL.

In some embodiments, the inner surfaces of gravity flow micro-physiological article200(e.g., the surfaces of flow channel204, supply chamber202, and divider209) that are in contact with the blood surrogate can be modified for reducing non-specific binding of a species in the blood surrogate to the inner surfaces of gravity flow micro-physiological article200. For example, at least one surface of the flow channel204, supply chamber202, divider209, or mixing chamber203in contact with the blood surrogate can be coated with a surfactant (e.g., PLURONIC® 127) or a blocking protein such as bovine serum albumin, for reducing cell or protein adhesion thereto. Additional surfactant that can be used to reduce the adhesive force between the surface of gravity flow micro-physiological article200and non-specific binding of a species in the blood surrogate can include hydrophilic (e.g., amphipathic) polymers and polymeric surface-acting agents; non-ionic agents such as polyhydric alcohol-type surfactants, e.g., fatty acid esters of glycerol, pentaerythritol, sorbitol, sorbitan, and more hydrophilic agents made by their alkoxylation, including polysorbates (TWEEN®); polyethylene glycol-type surfactants such as PLURONIC surfactants (e.g., poloxamers), polyethylene glycol (PEG), methoxypolyethylene glycol (MPEG), polyacrylic acid, polyglycosides, soluble polysaccharides, dextrins, microdextrins, gums, and agar; ionic agents, including anionic surfactants such as salts of carboxylic acids (soaps), sulfuric acids, sulfuric esters of higher alcohols; cationic surfactants such as salts of alkylamine type, quaternary ammonium salts, or amphoteric surfactants such as amino acid type surfactants and betaine type surfactants. The methods or reagents used to reduce non-specific binding of a species in the blood surrogate to the inner surfaces of gravity flow micro-physiological article200can be selected based on the material of substrate201or types of species to be blocked.

In accordance with the foregoing, it will be appreciated that gravity flow micro-physiological article200provides a reliable mufti-organ microphysiological cell culture system that can be used for large-scale drug screening with human primary and stem cells. Moreover, gravity flow micro-physiological article200can provide predictive data for drug candidates. Additionally, gravity flow micro-physiological article200can be used in drug development for testing of new compounds to save money on clinical trials. Beneficially, gravity flow micro-physiological article200overcomes limitation of conventional devices that cannot be used as a human body mimic and that have designs that are expensive to make, difficult to set up, and difficult to operate. Moreover, conventional devices include on-board MEMS components that can fail because they are exposed to liquid full of proteins that foul them and are prone to leaking. Conventional systems also do not capture the complexity of human organs. Gravity flow micro-physiological article200provides a fluidic infrastructure for an MPS in an inexpensive, easy-to-set-up, and easy-to-operate format, overcoming the limitation of conventional systems that have hindered adoption of this MPS. Gravity flow micro-physiological article200provides adjustment of biological parameters to make MPS mimic the human body more reliably than conventional technology and can test drugs fast and inexpensively to generate data for pharmaceutical studies.

Gravity flow micro-physiological article200is open and holds a cell culture medium inside its fluidic channels via surface tension. Gravity drives fluidic flow in gravity flow micro-physiological article200, and hydraulic resistances control flow rates therein so gravity flow micro-physiological article200operates in an absence of a mechanical fluid pump. Because gravity flow micro-physiological article200is open, leaking is not an issue.

Gravity flow micro-physiological article200as an MPS mimics the human body because gravity flow micro-physiological article200can include functional organ volume ratios, involve blood residence times per organ volume, and have a proportion of blood surrogate identical to or substantially equivalent to the human body. In addition, gravity flow micro-physiological article200can have a geometry and size of interconnecting fluid channels so that a combination of gravity forces, surface tension, and hydraulic resistances function to provide liquid flow at a physiological flow rate. Gravity flow micro-physiological article200can include a silicon chip that controls fluidic flow and a chip support that has low resistance channels for fluid recirculation and can be formed, e.g., microfabricated on a silicon wafer, using contact photolithography, and deep reactive ion etching. The chip support can be 3D-printed.

The flow rates and fluid residence times in various parts of gravity flow micro-physiological article200can be determined and compared with measured flow rates against calculations, including an influence of evaporation. Physiological flow rates and fluid residence times can be used with in vitro tissues so that gravity flow micro-physiological article200operates as a body mimic.

Gravity flow micro-physiological article200produces drug metabolites and recirculates those metabolites among organ mimics. Toxic metabolites reach all tissues. In an exemplary determination of a physiological response to a drug, gravity flow micro-physiological article200is loaded with primary tissues, and 5-urofluoracil (5-FU), a cancer prodrug, is added. Cell survival is determined from fluorescent viability dye. It is contemplated that a positive test produces a toxic, cancer-treating metabolite in a liver mimic that affects cancer tissues and regular tissues in other parts of gravity flow micro-physiological article200.

Advantageously, gravity flow micro-physiological article200overcomes leaking, becoming contaminating, or experiencing irregular flow because of air bubbles. The low success rate of conventional closed, pumped systems is a technical impediment of conventional articles to large-scale commercial success of conventional MPS. Gravity flow micro-physiological article200overcome those obstacles. Moreover, gravity flow micro-physiological article200can perform drug screening in repeated experiments that are performed in parallel to produce statistically sound datasets. Human actions add variation to data, and gravity flow micro-physiological article200reduces human intervention so that data taken from gravity flow micro-physiological article200may be more reliable than for conventional systems that involve more human interaction with loading, controlling, and sampling of conventional systems.

All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The ranges are continuous and thus contain every value and subset thereof in the range. Unless otherwise stated or contextually inapplicable, all percentages, when expressing a quantity, are weight percentages. The suffix (s) as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including at least one of that term (e.g., the colorant(s) includes at least one colorants). Option, optional, or optionally means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. As used herein, combination is inclusive of blends, mixtures, alloys, reaction products, collection of elements, and the like.

As used herein, a combination thereof refers to a combination comprising at least one of the named constituents, components, compounds, or elements, optionally together with one or more of the same class of constituents, components, compounds, or elements.

All references are incorporated herein by reference.

The use of the terms “a,” “an,” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. It can further be noted that the terms first, second, primary, secondary, and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. It will also be understood that, although the terms first, second, etc. are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. For example, a first current could be termed a second current, and, similarly, a second current could be termed a first current, without departing from the scope of the various described embodiments. The first current and the second current are both currents, but they are not the same condition unless explicitly stated as such.

The modifier about used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity), The conjunction or is used to link objects of a list or alternatives and is not disjunctive; rather the elements can be used separately or can be combined together under appropriate circumstances.