Pluripotent Stem Cells: Current Understanding and Future Directions

Figure 3

Schematic representation of culture conditions used to obtain primed and naïve pluripotent hESCs. (a) Conventional hESCs are derived from human blastocysts using a culture medium supplemented with bFGF and Activin A. hESCs derived in conventional culture conditions exhibit a pluripotent state more similar to murine EpiSCs than ESCs and are defined as primed hESCs. (b) hESCs with mESC-like characteristics can be produced by induced expression of either OCT4/KLF4 or KLF4/KLF2 transgenes in primed hESCs. Stable in vitro maintenance of these naïve hESCs requires continuous expression of the transgenes. (c, d, and e) Defined conditions allowing derivation of naïve hESCs from either already established primed hESCs or directly from blastocysts without the use of pluripotency-associated transgenes. (f) Conversion of primed hESCs into naïve state using five kinase inhibitors (5i) + LIF + Activin. (g) Short term expression of NANOG and KLF2 in primed hESC cells is sufficient to trigger ground state in hESCs cultivated in 2iL medium plus PKC inhibitor Gö6983.