Cell preservation method for pluripotent stem cells

1. A method for freezing a pluripotent stem cell, the method including the steps of providing a pluripotent stem cell suspension, performing ice nucleation on the pluripotent stem cell suspension by rapidly lowering the temperature of the suspension to a nucleating point at a rate from about −5° C./minute to about −55° C./minute to provide an ice nucleated pluripotent stem cell suspension, and lowering the temperature of the ice nucleated pluripotent stem cell suspension to a temperature sufficiently low to allow long term storage of the pluripotent stem cell, wherein upon thawing, the pluripotent stem cell retains pluripotency, and wherein the pluripotent stem cell is a human embryonic stem cell.

2. The method according to claim 1 wherein upon thawing the pluripotent stem cell is capable of differentiating into a cell type selected from the group consisting of a hepatic cell, a renal cell, a dermal cell, a cardiovascular cell, a neural cell, a skeletal cell, a pancreatic cell and a reproductive cell.

3. The method according to claim 1 wherein upon thawing the pluripotent stem cell is capable of differentiating into a cell type selected from the group consisting of a gut epithelial cell, a chondrocyte, an osteocyte, a cardiomyocyte-like cell, a beta-like cell, and a hair follicle cell.

4. The method according to claim 1 wherein the ice nucleation step includes lowering the temperature of the pluripotent stem cell suspension to a temperature of from about −11° C. to about −13° C.

5. The method according to claim 4 wherein the temperature of the pluripotent stem cell suspension is lowered to a temperature of about −12.1° C.

6. The method according to claim 4 wherein the temperature of the pluripotent stem cell suspension is lowered at a rate of from about −5° C./minute to about −15° C./minute.

7. The method according to claim 6 wherein the pluripotent stem cell suspension is lowered at a rate of about −9° C./minute.

8. The method according to claim 4 wherein the temperature of the pluripotent stem cell suspension at the end of the ice nucleation step is about −12.1° C.

9. The method according to claim 1 wherein the pluripotent stem cell suspension is kept for a period at the temperature at which ice-nucleation is performed to allow the formation of an adequate seed or seeds in the pluripotent stem cell.

10. The method according to claim 9 wherein the period is about 5 minutes.

11. The method according to claim 1 wherein the pluripotent stem cell suspension is subjected to a cold activation step before the ice nucleation step.

12. The method according to claim 11 wherein the cold activation step includes cooling the pluripotent stem cell suspension to a temperature of from about −4° C. to about −12° C.

13. The method according to claim 11 wherein the cold activation step includes cooling the pluripotent stem cell suspension to about −8° C.

14. The method according to claim 11 wherein the cold activation step includes cooling the pluripotent stem cell suspension at a rate of about −1° C./minute.

15. The method according to claim 11 wherein the ice nucleation step is performed by lowering the temperature of the pluripotent stem cell suspension from the temperature at the conclusion of the cold activation step to a temperature of about −10° C. to about −12° C.

16. The method according to claim 15 wherein the temperature is about −10.9° C.

17. The method according to claim 15 wherein the temperature is lowered rapidly at a rate of from about −15° C./minute to about −55° C./minute.

18. The method according to claim 17 wherein the temperature is lowered at a rate of from about −35° C./minute to about −38° C./minute.

19. The method according to claim 1 wherein the pluripotent stem cell suspension is subjected to a soak step after the cold activation step and/or before the ice nucleation step.

20. The method according to claim 19 wherein the soak step includes maintaining the pluripotent stem cell suspension at the final temperature achieved by the cold activation step for a period of from about 5 minutes to about 10 minutes.

21. The method according to claim 1 wherein following the ice nucleation step, the temperature of the pluripotent stem cell suspension is lowered from the nucleating point to a solidification point.

22. The method according to claim 1 including a dehydration step after the ice nucleation step whereby the temperature of the pluripotent stem cell suspension is lowered to a temperature of from about −35° C. to about −38° C.

23. The method according to claim 22 the temperature of the pluripotent stem cell suspension is lowered at a rate of about −0.8° C./minute.

24. The method according to claim 1 wherein after the ice nucleation or dehydration step, the temperature of the pluripotent stem cell suspension is decreased rapidly to a temperature of about −180° C.

25. The method according to claim 1 wherein the pluripotent stem cell suspension does not contain an exogenous biological cryoprotectant.

26. The method according to claim 25 wherein the exogenous biological cryoprotectant is serum.

27. The method according to claim 1 wherein a pluripotent stem cell parameter is substantially unchanged after thawing, the pluripotent stem cell parameter including viability and/or the ability to differentiate under appropriate stimulus.

28. The method according to claim 1 wherein upon thawing the population of pluripotent stem cells the pluripotent stem cell suspension has a viability of up to 90%.

29. The method according to claim 1 wherein upon thawing the pluripotent stem cell retains an undifferentiated phenotype.

30. The method according to claim 1 wherein upon thawing the pluripotent stem cell exhibits non-cystic growth.

31. The method according to claim 1 wherein after thawing the pluripotent stem cell retains a marker selected from the group consisting of Oct-4, TRA 1-60, TRA 1-81, SSEA-3 and SSEA-4.

32. The method according to claim 1 wherein upon thawing the pluripotent stem cell exhibits negligible retention of the marker SSEA-1.

33. The method according to claim 1 wherein upon thawing the pluripotent stem cell is capable of differentiating in vivo or in vitro into an endodermal, mesodermal or ectodermal cell.

34. The method according to claim 1 wherein a pluripotent stem cell stored frozen for at least 2 months retains pluripotency.

35. The method according to claim 1 wherein upon thawing the pluripotent stem cell exhibits a normal karyotype.

36. The method according to claim 1 wherein upon thawing the pluripotent stem cell exhibits a normal growth rate.