Ex vivo proliferation of epithelial cells

1. A method for proliferating epithelial cells ex vivo, comprising:

expanding the number of cells in an originating epithelial cell population comprising differentiated epithelial cells under serum-free and feeder-cell free expansion culture conditions, thereby generating an expanded epithelial cell population, wherein the expansion culture conditions comprise one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population, and

activating telomerase reverse transcriptase in the epithelial cell population.

2. The method of claim 1 , wherein the one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population comprise one or more transforming growth factor beta (TGF-beta) receptor inhibitors.

3. The method of claim 1 , wherein the one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population comprise one or more SMAD signaling inhibitors.

4. The method of claim 3 , wherein the one or more SMAD signaling inhibitors comprise one or more inhibitors chosen from SMAD1 signaling inhibitors, SMAD2 signaling inhibitors, SMAD3 signaling inhibitors, SMAD4 signaling inhibitors, and SMAD5 signaling inhibitors.

5. The method of claim 1 , the one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population comprise one or more ALK5 inhibitors.

6. The method of claim 5 , wherein the one or more ALK5 inhibitors are selected from A83-01, GW788388, RepSox, and SB 431542.

7. The method of claim 1 , wherein the expansion culture conditions comprise a second agent that modulates cytoskeletal structure in the population.

8. The method of claim 7 , wherein the second agent comprises an inhibitor selected from a Rho-associated protein kinase inhibitor, a p21-activated kinase (PAK) inhibitor, and a myosin II inhibitor.

9. The method of claim 8 , wherein the Rho-associated protein kinase inhibitor is selected from Y-27632, SR 3677, thiazovivin, HA1100 hydrochloride, HA1077 and GSK-429286.

10. The method of claim 8 , wherein the PAK inhibitor is IPA3.

11. The method of claim 8 , wherein the myosin II inhibitor is blebbistatin.

12. The method of claim 1 , wherein the expansion culture conditions further comprise a beta-adrenergic receptor agonist.

13. The method of claim 12 , wherein the beta-adrenergic receptor agonist is isoproterenol.

14. The method of claim 1 , wherein the expansion culture conditions comprise calcium at a concentration below 200 μM.

15. The method of claim 1 , wherein the expansion culture conditions comprise calcium at a concentration below 100 μM.

16. The method of claim 1 , wherein the expansion culture conditions comprise one or more mitogenic growth factors.

17. The method of claim 16 , wherein the one or more mitogenic growth factors comprise EGF, FGF, or EGF and FGF.

18. The method of claim 7 , wherein the originating epithelial cell population is capable of 25 population doublings or more when cultured under the expansion culture conditions; and the originating epithelial cell population is capable of no more than 20 population doublings when cultured under control culture conditions that do not include the one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population.

19. The method of claim 18 , wherein the originating epithelial cell population is capable of 50 population doublings or more when cultured under the expansion culture conditions.

20. The method of claim 18 , wherein the originating epithelial cell population is capable of 80 population doublings or more when cultured under the expansion culture conditions.

21. The method of claim 18 , wherein the originating epithelial cell population is capable of 100 population doublings or more when cultured under the expansion culture conditions.

22. The method of claim 1 , wherein the originating epithelial cell population is capable of expanding 5-fold or more over 5 days when cultured under the expansion culture conditions; and the originating epithelial cell population is capable of expanding no more than 2-fold over 5 days when cultured under control culture conditions that do not include the one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population.

23. The method of claim 1 , wherein the originating epithelial cell population is capable of expanding 10-fold or more over 5 days when cultured under the expansion culture conditions; and the originating epithelial cell population is capable of expanding no more than 2-fold over 5 days when cultured under control culture conditions that do not include the one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population.

24. The method of claim 1 , wherein the expansion culture conditions do not comprise one or more of extracellular matrix comprising heterogeneous components, a Wnt agonist or a beta-catenin agonist.

25. The method of claim 1 , wherein the originating epithelial cell population is derived from differentiated tissue.

26. The method of claim 1 , wherein the originating epithelial cell population is derived from embryonic stem (ES) cells.

27. The method of claim 1 , wherein the originating epithelial cell population is derived from induced pluripotent stem cells (iPSCs).

28. The method of claim 1 , wherein the originating epithelial cell population does not comprise pluripotent cells.

29. A method for genetically modifying cells, comprising contacting cells with one or more agents that introduce a genetic modification to the cells, wherein the cells have been expanded by a method comprising:

expanding the number of cells in an originating epithelial cell population comprising differentiated epithelial cells under serum-free and feeder-cell free expansion culture conditions, thereby generating an expanded epithelial cell population, wherein the expansion culture conditions comprise one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population, and

activating telomerase reverse transcriptase in the epithelial cell population.

30. The method of claim 1 , wherein the originating epithelial cell population comprises genetically modified cells.

31. The method of claim 1 , wherein the originating epithelial cell population comprises a stable transgenic cell line.

32. The method of claim 29 , the one or more agents that inhibit transforming growth factor beta (TGF-beta) signaling in the population comprise one or more ALK5 inhibitors.

33. The method of claim 32 , wherein the one or more ALK5 inhibitors are selected from A83-01, GW788388, RepSox, and SB 431542.

34. The method of claim 29 , wherein the expansion culture conditions comprise a second agent that modulates cytoskeletal structure in the population.

35. The method of claim 34 , wherein the second agent comprises an inhibitor selected from a Rho-associated protein kinase inhibitor, a p21-activated kinase (PAK) inhibitor, and a myosin II inhibitor.

36. The method of claim 35 , wherein the Rho-associated protein kinase inhibitor is selected from Y-27632, SR 3677, thiazovivin, HA1100 hydrochloride, HA1077 and GSK-429286.

37. The method of claim 35 , wherein the PAK inhibitor is IPA3.

38. The method of claim 35 , wherein the myosin II inhibitor is blebbistatin.

39. The method of claim 29 , wherein the expansion culture conditions comprise calcium at a concentration below 100 μM.