Substrates for high-density cell growth and metabolite exchange
Manufacturing techniques for fabricating a polymer or other substrate optimized for growing cells is described, which takes the form of a micro-thin bag with gas permeable sides. Sides of the bag can be held at a fixed distance from one another with a multitude of tiny micropillars or other spacers extending between them, keeping the bag at a predetermined thickness and preventing the bag from collapsing and the sides from sticking together. In other embodiments, the sides may be held apart by gas pressure alone. A 0.01 μm to 1000 μm parylene or other biocompatible coating over the bag outsides controls the permeability of the bag material and provides a bio-safe area for cell growth. An alternate configuration uses open-cell foam with skins coated with a biocompatible coating. Tubes going into multiple bags can be connected to a manifold that delivers gaseous oxygen or removes carbon dioxide and other waste gases. Multiple bags can be stacked together tightly, with o-ring spacers in between, and housed within a vessel to form a high-surface area, ultra-compact cell growing system. For cells growing on the bags, liquid nutrients can be fed by way of the tube spacers, and oxygen and waste gases permeated through the bag sides and transported within the bags.
1 . A method of manufacturing a cell growing device, the method comprising: casting a pillared gas permeable sheet having spacers on one side, the gas permeable sheet having a thickness sufficient to allow gaseous molecular oxygen to permeate therethrough yet prevent liquid water from permeating therethrough at standard room temperature and atmospheric pressure; fabricating a second gas permeable sheet; joining the second gas permeable sheet to the pillared gas permeable sheet with the spacers therebetween; hermetically sealing a perimeter of the gas permeable sheets together to form an expansion resistant bag; depositing a biocompatible coating on at least one side of the expansion resistant bag, the biocompatible coating having a thickness between 0.1 μm and 1000 μm, wherein the biocompatible coating includes a parylene coating selected from the group consisting of parylene N, parylene C, parylene D, and parylene AF-4; and treating the biocompatible coating in order to improve cell adhesion.
2 . The method of claim 1 wherein the pillared gas permeable sheet and second gas permeable sheet are comprised of a polymer, and each sheet has a thickness less than 200 μm.
3 . The method of claim 1 further comprising:
forming an inlet in the expansion resistant bag.
4 . The method of claim 1 further comprising:
applying adhesive to the second gas permeable sheet.
5 . A method of manufacturing a cell growing device, the method comprising:
intimately contacting a pair of gas permeable, polymer sheets together;
placing a heat-insulative mask having an array of through holes against the polymer sheets;
pressing a heated iron against the heat-insulative mask opposite the polymer sheets, a temperature of the heated iron and duration of the pressing sufficient to form an array of welds between the polymer sheets where exposed by the mask through holes;
hermetically sealing a perimeter of the polymer sheets together to form a bag with an interior portion;
depositing a biocompatible coating on at least one side of the bag, the biocompatible coating having a thickness between 0.1 μm and 1000 μm; and
treating the biocompatible coating in order to improve cell adhesion.
6 . The method of claim 5 wherein the array of through holes were photolithographically formed in the mask.
7 . The method of claim 5 wherein the polymer sheets comprise polydimethylsiloxane (PDMS), and the heat-insulative mask comprises silicone rubber.
8 . The method of claim 5 wherein the through holes have a center-to-center spacing less-than-or-equal-to 2000 μm.
9 . The method of claim 5 further comprising:
attaching a plurality of outside spacers on an outside of the bag.
10 . The method of claim 9 wherein the outside spacers are porous tubes.
11 . The method of claim 9 wherein the outside spacers are spheres coated with a biocompatible coating.
12 . The method of claim 5 wherein the biocompatible coating includes a parylene coating selected from the group consisting of parylene N, parylene C, parylene D, and parylene AF-4.
13 . The method of claim 5 further comprising:
applying agarose, collagen, lactic acid, laminin, poly-D-lysine, or poly-L-lysine on the biocompatible coating.
14 . The method of claim 1 wherein the spacers have a center-to-center spacing less-than-or-equal-to 2000 μm.
15 . The method of claim 1 wherein the gas permeable sheets comprise polydimethylsiloxane (PDMS).
16 . A method of manufacturing a cell growing device, the method comprising: casting a pillared gas permeable sheet having spacers on one side, the gas permeable sheet having a thickness sufficient to allow gaseous molecular oxygen to permeate therethrough yet prevent liquid water from permeating therethrough at standard room temperature and atmospheric pressure; fabricating a second gas permeable sheet; joining the second gas permeable sheet to the pillared gas permeable sheet with the spacers therebetween; hermetically sealing a perimeter of the gas permeable sheets together to form an expansion resistant bag; depositing a biocompatible coating on at least one side of the expansion resistant bag, the biocompatible coating having a thickness between 0.1 μm and 1000 μm; and attaching a plurality of outside spacers on an outside of the bag wherein the outside spacers include porous tubes.
17 . The method of claim 16 wherein the outside spacers include spheres coated with a biocompatible coating.
18 . The method of claim 16 wherein the biocompatible coating includes a parylene coating selected from the group consisting of parylene N, parylene C, parylene D, and parylene AF-4.
19 . The method of claim 1 further comprising:
applying agarose, collagen, lactic acid, laminin, poly-D-lysine, or poly-L-lysine on the biocompatible coating.
20 . The method of claim 16 wherein the pillared gas permeable sheet and second gas permeable sheet are comprised of a polymer, and each sheet has a thickness less than 200 μm.