Compositions and methods useful for culturing differentiable cells
The present invention relates to cell culture methods and compositions that are essentially serum-free and comprise a basal salt nutrient solution and an ErbB3 ligand.
1. A composition comprising pluripotent stem cells, a basal salt nutrient solution and an ErbB3 ligand, said composition being essentially free of serum, wherein the pluripotent stem cells can give rise to all three germ layers, and wherein the ErbB3 ligand binds to an ErbB3 receptor, which in turn dimerizes to an ErbB2 receptor to form an ErbB2/ErbB3 heterodimer, thereby activating the tyrosine kinase activity of the ErbB2 receptor in the ErbB2/ErbB3 heterodimer.
2. The composition of claim 1 , wherein said composition is free of exogenous insulin and insulin substitutes.
3. The composition of claim 2 , further comprising insulin-like growth factor or a functional fragment thereof.
4. The composition of claim 2 , wherein said ErbB3 ligand is selected from the group consisting of Neuregulin-1, Heregulin-β(HRG-β), Heregulin-α(HRG-α), Neu differentiation factor (NDF), acetylcholine receptor-inducing activity (ARIA), glial growth factor 2 (GGF2), motor-neuron derived factor (SMDF), Neuregulin-2, Neuregulin-2β(NRG2-β), Epiregulin, Biregulin and functional fragments thereof.
5. The composition of claim 4 , wherein said ErbB3 ligand is HRG-β or a functional fragment thereof.
6. The composition of claim 5 , further comprising transforming growth factor beta (TGF-β), a TGF-β family member or a functional fragment thereof.
7. The composition of claim 6 , wherein said TGF-β family member is selected from the group consisting of Nodal, Activin A, Activin B, bone morphogenic protein-2 (BMP2), bone morphogenic protein-4 (BMP4), and functional fragments thereof.
8. The composition of claim 7 , wherein said TGF-β family member is Activin A.
9. The composition of claim 8 , further comprising insulin-like growth factor or a functional fragment thereof.
10. The composition of claim 9 , wherein said composition is free of exogenous fibroblast growth factor.
11. The composition of claim 9 , further comprising at least one fibroblast growth factor (FGF) selected from the group consisting of FGF-2, FGF-7, FGF-10, FGF-22 and variants functional fragments thereof.
12. The composition of claim 11 , wherein said at least one FGF is FGF-7, FGF-10 and FGF-22.
13. The composition of claim 12 , further comprising a serum albumin (SA).
14. The composition of claim 13 , wherein the SA is bovine SA (BSA) or human SA (HSA).
15. The composition of claim 14 , wherein the concentration of the SA is more than about 0.2%, volume to volume (v/v).
16. The composition of claim 14 , wherein the concentration of SA is less than about 5% v/v.
17. A composition comprising pluripotent stem cells, a basal salt nutrient solution and a means for stimulating ErbB2-directed tyrosine kinase activity in said pluripotent stem cells.
18. The composition of claim 17 , wherein said means for stimulating ErbB2-directed tyrosine kinase activity comprises at least one ligand that specifically binds ErbB3 in said pluripotent stem cells.
19. The composition of claim 18 , wherein the pluripotent stem cells are primate embryonic stem cells.
20. The composition of claim 1 , wherein the pluripotent stem cells are selected from the group consisting of ES cells, EPL cells, ICM/epiblast cells, EG cells, and pluripotent cells derived by dedifferentiation or nuclear transfer.