Bioreactor for cell growth and associated methods

Abstract

Apparatuses, systems, and methods are provided for growing and maintaining cells. A three-dimensional matrix, such as a hydrogel material, is seeded with cells and placed in a bioreactor having two compartments. The matrix is supported between the two compartments by first and second porous materials, which engage opposing surfaces of the matrix. A first media stream having certain properties is propagated through the first compartment, where it contacts one surface of the matrix via the first porous material. A second media stream having different properties is propagated through the second compartment such that it contacts the opposite surface of the matrix via the second porous material. Through migration of each stream at least partially into the matrix, various controlled gradients may be established within the matrix, encouraging growth of the cells. Such gradients include osmotic pressure, oscillating osmotic pressure, hydrostatic pressure, oxygen tension, and/or nutrient gradients.

1 . An apparatus for growing and maintaining cells comprising:
 a first compartment including a first inlet configured to alternately receive a first media solution and a third media solution, a first outlet in fluid communication with the first inlet, and a first porous material disposed within the first compartment;   a second compartment including a second inlet configured to receive a second media solution, a second outlet in fluid communication with the second inlet, and a second porous material disposed within the second compartment; and   a hydrogel material seeded with cells, disposed between the first compartment and the second compartment, and at least partially supported on a first surface of the hydrogel material by the first porous material and on an opposite second surface of the hydrogel material by the second porous material;   wherein the first media solution is different from the second media solution, wherein the first and second compartments are configured such that propagation of the first media solution through the first compartment and propagation of the second media solution through the second compartment establishes a controlled gradient across a thickness of the hydrogel material, and wherein the third media solution has a different osmolality than the first media solution such that alternate propagation of the first and third media solutions through the first compartment creates an oscillating osmotic pressure gradient across the thickness of the hydrogel material.   
     
     
         2 . The apparatus of  claim 1 , wherein the hydrogel material is seeded with cells comprising chondrocytes. 
     
     
         3 . The apparatus of  claim 1 , wherein the hydrogel material comprises at least one substance selected from the group consisting of sodium alginate, agarose, hyaluronic acid, chondroiton sulfate, collagen, proteoglycan, and cell adhesion peptides. 
     
     
         4 . The apparatus of  claim 1 , wherein the first and second compartments are configured to allow the first media solution and the third media solution, respectively, to contact the first surface of the hydrogel material and the second media solution to contact the second surface of the hydrogel material, and wherein the first media solution and the third media solution are permitted to contact the second media solution only within the hydrogel material. 
     
     
         5 . The apparatus of  claim 1  further comprising:
 a spacer element disposed between the first and second compartments, wherein the spacer element is configured to partially surround the hydrogel material and to permit sealing of the first surface of the hydrogel material with a portion of the first compartment and sealing of the second surface of the hydrogel material with a portion of the second compartment. 
 
     
     
         6 . The apparatus of  claim 1 , wherein the first compartment is configured to receive the first media solution having a first osmolality and the second compartment is configured to receive the second media solution having a second osmolality that is different from the first osmolality. 
     
     
         7 . The apparatus of  claim 1 , wherein the first compartment is configured to receive the first media solution having a first oxygen content and the second compartment is configured to receive the second media solution having a second oxygen content that is different from the first oxygen content such that an oxygen tension gradient is established across the thickness of the hydrogel. 
     
     
         8 . The apparatus of  claim 1 , wherein the first compartment is configured to receive the first media solution having a first nutrient content and the second compartment is configured to receive the second media solution having a second nutrient content that is different from the first nutrient content such that a nutrient gradient is established across the thickness of the hydrogel. 
     
     
         9 . The apparatus of  claim 1 , wherein the first compartment is configured to receive the first media solution at a predetermined flow rate that varies as a function of time and the second compartment is configured to receive the second media solution at a generally constant flow rate. 
     
     
         10 . The apparatus of  claim 1 , wherein each of the first and second inlets and the first and second outlets has an orifice, and wherein the orifice of the first inlet has a larger cross-sectional area than the orifice of the first outlet and the orifice of the second inlet has approximately the same cross-sectional area as the orifice of the second outlet, such that the hydrostatic pressure in the first compartment is greater than the hydrostatic pressure in the second compartment and creates a hydrostatic pressure gradient across the thickness of the hydrogel. 
     
     
         11 . (canceled) 
     
     
         12 . A system for growing and maintaining cells comprising:
 a bioreactor including:
 a first compartment having a first inlet, a first outlet in fluid communication with the first inlet, and a first porous material disposed within the first compartment; 
 a second compartment adjacent the first compartment including a second inlet, a second outlet in fluid communication with the second inlet, and a second porous material disposed within the second compartment; and 
 a hydrogel material seeded with cells, disposed between the first compartment and the second compartment, and at least partially supported on a first surface of the hydrogel material by the first porous material and on an opposite, second surface of the hydrogel material by the second porous material; 
   a source of a first media solution in fluid communication with the first inlet; and   a source of a second media solution that is different than the first media solution, wherein the source of the second media solution is in fluid communication with the source of the first media solution and at least one of the first and second inlets; and   a source of a third media solution having a different osmolality than the first and second media solutions, wherein the first and third media solutions are alternately propagated through the first compartment and the second media solution is propagated through the second compartment to create an oscillating osmotic pressure gradient across the thickness of the hydrogel material.   
     
     
         13 . The system of  claim 12  further comprising:
 a pump in fluid communication with at least one of the sources and configured to propagate at least one of the media solutions through at least one of the first and second compartments; and 
 a controller configured to control the pump such that a solution comprising at least one of the first or third media solutions is propagated through the first compartment via the first inlet and the second media solution is propagated through the second compartment via the second inlet. 
 
     
     
         14 . The system of  claim 12 , wherein the first media solution is propagated at a predetermined flow rate that varies as a function of time and the second media solution is propagated at a generally constant flow rate such that a hydrostatic pressure gradient that varies as a function of time is established across the thickness of the hydrogel. 
     
     
         15 . The system of  claim 12  further comprising a pinch valve between the sources of the first and second media solutions and the first compartment, wherein the pinch valve is configured to allow a flow of the first media solution from the respective source to the first inlet and to allow a flow of a solution comprising the first and second media solutions from both the respective sources to the first inlet, and wherein the third media solution is a combination of the first and second media solutions, such that the source of the third media solution comprises the source of the first media solution and the source of the second media solution. 
     
     
         16 . The system of  claim 12 , wherein the first media solution has a first osmolality and the second media solution has a second osmolality that is different from the first osmolality such that an osmotic pressure gradient is established across the thickness of the hydrogel. 
     
     
         17 . The system of  claim 12 , wherein the first media solution has a first oxygen content and the second media solution has a second oxygen content that is different from the first oxygen content such that an oxygen tension gradient is established across the thickness of the hydrogel. 
     
     
         18 . The system of  claim 12 , wherein the first media solution has a first nutrient content and the second media solution has a second nutrient content that is different from the first nutrient content such that a nutrient gradient is established across the thickness of the hydrogel. 
     
     
         19 . (canceled) 
     
     
         20 . The system of  claim 12  further comprising a first sample port downstream of the first outlet and a second sample port downstream of the second outlet, wherein the first and second sample ports are configured to provide access to media exiting the first and second compartments through the first and second outlets, respectively. 
     
     
         21 - 37 . (canceled) 
     
     
         38 . The apparatus of  claim 1 , wherein each of the first and second compartments comprises a ridge configured to engage an edge region of the hydrogel material and to create a seal with the first and second surfaces of the hydrogel. 
     
     
         39 . The apparatus of  claim 5 , wherein each of the first and second compartments defines a channel configured to receive a sealing member, wherein each sealing member is configured to engage a corresponding surface of the spacer element.