Derivation of Maternal Epiblast Stem Cells from Haploid Embryos

Pluripotent cells in the inner cell mass (ICM) or epiblast of mammalian embryos exhibit the capacity to differentiate into all cells represented in the three germ layers. Embryonic stem (ES) cells can be derived from the ICM of preimplantation stage blastocysts, while epiblast stem cells (EpiSCs) can be derived from the epiblast of postimplantation embryos or preimplantation stage embryos. The ability to derive distinct types of pluripotent cells from blastocyst-stage embryos suggests that optimization of culture conditions can promote self-renewal of various stem cell populations. Moreover, because mouse EpiSCs resemble human pluripotent stem (hPS) cells, EpiSCs are a useful model to study common and divergent mechanisms of self-renewal between orthologous species. In addition, studies have demonstrated that haploid embryos and ES cells can be derived from chemically activated oocytes. Here, we describe a protocol for deriving maternal (parthenogenetic/gynogenetic) EpiSCs (maEpiSCs) from haploid blastocyst-stage embryos. This protocol is suitable to establish an experimental model for the study of mechanisms of EpiSC self-renewal and differentiation.