Mouse postimplantation epiblast cultured in activin and basic fibroblast growth factor gives rise to continuously growing epiblast stem cells (EpiSCs) that share key properties with postimplantation epiblast, such as DNA methylation and an inactive X-chromosome. EpiSCs also show a distinct gene expression profile compared to embryonic stem cells (ESCs) derived from preimplantation blastocysts, and do not contribute efficiently to chimeras. EpiSCs can, however, revert to pluripotent ESC-like cells upon exposure to leukemia inhibitory factor–Stat3 signalling on feeder cells. Here we describe a protocol for the establishment of EpiSCs and their reversion to ESCs.
