Alginate polyelectrolyte encapsulation of embryonic stem cells

1. An isolated cell population comprising:

a single cell suspension of embryonic stem cells (ES cells) encapsulated within an alginate polyelectrolyte microenvironment, wherein the encapsulated ES cells are capable of differentiating within said microenvironment into hepatocyte lineage cells in the absence of embryoid body intermediates or growth factor supplementation, wherein at least about 80% of the cell population is capable of differentiating into the hepatocyte lineage cells within the alginate polyelectrolyte microenvironment.

2. The cell population of claim 1 , wherein the alginate polyelectrolyte microenvironment comprises poly-L-lysine.

3. The cell population of claim 1 , wherein the alginate polyelectrolyte microenvironment comprises a divalent cation.

4. The cell population of claim 3 , wherein the divalent cation is Ca 2+ or Ba 2+ .

5. The cell population of claim 1 , wherein the ES cells are positive for a cell surface marker selected from the group consisting of SSEA4, Tra-1-60, Tra-1-81, Oct-4 and combinations thereof.

6. The cell population of claim 1 , wherein the hepatocyte lineage cells are positive for a cell surface marker selected from the group consisting of CD34, CD38, C-kit and combinations thereof.

7. The cell population of claim 1 , wherein the hepatocyte lineage cells produce albumin.

8. The cell population of claim 1 , wherein the hepatocyte lineage cells secrete urea.

9. The cell population of claim 1 , wherein the hepatocyte lineage cells express a polypeptide selected from the group consisting of cytochrome P450 subunit 1a1, cytochrome P450 subunit 1a2, cytochrome P450 subunit 1b1, cytochrome P450 subunit 2b9, cytochrome P450 subunit 2b13, cytokeratin 18, connexin 32, alpha-fetoprotein, transthyretin, alpha-1-antitrypsin, tyrosine aminotransferase and combinations thereof.

10. The cell population of claim 1 , wherein the alginate polyelectrolyte microenvironment is in the form of a polymerized bead.

11. The cell population of claim 10 , wherein the bead size is about 500 μm.

12. The cell population of claim 10 , wherein the bead is formed at a cell seeding density of about 1×10 6 cells/ml to about 1×10 7 cells/ml.

13. The cell population of claim 10 , wherein the bead is formed at a cell seeding density of about 5×10 6 cells/ml.

14. The cell population of claim 10 , wherein the bead is formed at an alginate concentration of from about 1.7% (w/v) to about 2.5% (w/v).

15. The cell population of claim 10 , wherein the bead is formed at an alginate concentration of about 2.0% (w/v).

16. The cell population of claim 1 , wherein the alginate polyelectrolyte microenvironment of the encapsulated ES cells does not promote hepatocyte function in undifferentiated ES cells.

17. The cell population of claim 1 , wherein the alginate polyelectrolyte microenvironment of the encapsulated ES cells does promote hepatocyte function in hepatocyte differentiated ES cells.

18. The cell population of claim 1 , wherein the embryonic stem cells are reversibly encapsulated.

19. A method for producing encapsulated embryonic stem (ES) cells, comprising:

providing a single cell suspension of ES cells;

combining the single cell suspension of ES cells with an alginate solution to form a mixture;

subjecting the mixture to an electrostatic field to form electrostatic alginate droplets;

exposing the electrostatic alginate droplets to a divalent cation solution to form a bead about the ES cells;

allowing the bead to polymerize in the presence of the divalent cation solution; and

contacting the polymerized bead with a polyelectrolyte solution.

20. The method of claim 19 , wherein the polyelectrolyte solution comprises poly-L-lysine.

21. The method of claim 19 , wherein the final cell density after the combining step is about from 1×10 6 cells/ml to about 1×10 7 cells/ml.

22. The method of claim 19 , wherein the final cell density after the combining step is about 5×10 6 cells/ml.

23. The method of claim 19 , wherein the alginate concentration after the combining step is about 2.0% (w/v).

24. The method of claim 20 , wherein the concentration of the poly-L-lysine during the contacting is about 0.05% (w/v).

25. A method for increasing the yield of embryonic stem cells, the method comprising:

encapsulating a single cell suspension of ES cells within an alginate polyelectrolyte microenvironment comprising a polymerized bead formed at an alginate concentration of from about 1.7% (w/v) to about 2.5% (w/v);

culturing the encapsulated cells in cell media comprising a differentiation inhibitory factor to maintain an undifferentiated phenotype for the encapsulated cells; and

allowing the encapsulated undifferentiated ES cells to expand in culture while in the presence of the differentiation inhibitory factor.

26. The method of claim 25 , further comprising depolymerizing the bead in the presence of a chelating agent after the allowing step.

27. The method of claim 26 , further comprising recovering the expanded cells from the depolymerized beads.

28. The method of claim 26 , wherein the depolymerizing comprises removing the cell media; washing the beads; and adding to the washed beads a solution comprising the chelating agent.

29. The method of claim 25 , wherein the alginate polyelectrolyte microenvironment comprises poly-L-lysine.

30. The method of claim 25 , wherein the alginate polyelectrolyte microenvironment comprises a divalent cation.

31. The method of claim 25 , wherein the bead size is about 500 μm.

32. A kit comprising:

a single cell suspension of embryonic stem cells (ES cells) encapsulated within an alginate polyelectrolyte microenvironment, wherein the encapsulated ES cells are capable of differentiating within said microenvironment into hepatocyte lineage cells in the absence of embryoid body intermediates or growth factor supplementation.