Membrane

1. A composition comprising: (a) a membrane for supporting growth of cells, the membrane being non-biodegradable and porous, wherein pores of said membrane are between approximately 0.3 μm and 0.45 μm diameter, wherein pore density of the membrane is between 1×10 7 and 3×10 8 pores per cm 2 , and (b) a layer of retinal pigment epithelial cells, or retinal pigment epithelial cell precursors, or retinal derivative cells formed from the differentiation of retinal pigment epithelial cells on the membrane.

2. A composition according to claim 1 wherein the membrane hydraulic conductance of the membrane is more than 50×10 −10 in sec −1 Pa −1 .

3. A composition according to claim 1 wherein the membrane is sterilised by gamma irradiation, ethylene oxide, autoclaving or UV sterilization without degrading.

4. A composition according to claim 1 , wherein the membrane is sealed by ultrasonic sealing, radio frequency sealing or insert molding.

5. A composition according to claim 1 , wherein said membrane has a maximum thickness of approximately 11 μm.

6. A composition according to claim 1 , wherein said membrane has a maximum weight of approximately 1.5 mg/cm 2 .

7. A composition according to claim 1 , wherein the membrane is hydrophilic.

8. A composition according to claim 1 , wherein said membrane has a pH of 4 to 8.

9. A composition according to claim 1 , wherein said membrane comprises a coating on at least one side.

10. A composition according to claim 9 , wherein the coating is laminin, matrigel, fibronectin, or PLGA.

11. A composition according to claim 9 , comprising a pharmacological or biological agent, bound to the coating.

12. A composition according to claim 1 , wherein the cells are human retinal pigmented epithelial cells.

13. A composition according to claim 12 , wherein the cells are immortalized cells.

14. A composition according to claim 1 , wherein the membrane is made from a hydrophilic polymer selected from the group consisting of: a polyester, a polyurethane, a polyurea-urethane, a polyamide, a polyether-ester, a polycarbonate, a polyacrylate, poly(tetrafluoroethene), a polysiloxane, a polyolefin, and polyoxymethylene.

15. A method for using a composition according to claim 1 , comprising:

transplanting the membrane into an eye.

16. A composition comprising (a) a membrane for supporting the growth of cells, the membrane being made from a polyester and comprising a substantially no-biodegradable and porous support layer having a maximum thickness of between 9 μm and 11 μm and coated on at least one side with a coating comprising a glycoprotein, the pores being approximately 0.4 μm in diameter, wherein the pore density of the pores in the support layer is approximately 1×10 8 pores per cm 2 ; and (b) a layer of retinal pigment epithelial cells, or retinal pigment epithelial cell precursors, or retinal derivative cells formed from the differentiation of retinal pigment epithelial cells on the membrane.

17. A composition according to claim 14 wherein the hydrophilic polymer is polyester.

18. A composition according to claim 12 wherein the retinal pigment epithelial cells originate from human embryonic stem cells.