Generation of Mouse Parthenogenetic Epiblast Stem Cells and Their Imprinting Patterns.

Pluripotent stem cells can be established from parthenogenetic embryos, which only possess maternal alleles with maternal-specific imprinting patterns. Previously, we and others showed that parthenogenetic embryonic stem cells (pESCs) and parthenogenetic induced pluripotent stem cells (piPSCs) progressively lose the bimaternal imprinting patterns. As ESCs and iPSCs are naive pluripotent stem cells, parthenogenetic primed pluripotent stem cells have not yet been established, and thus, their imprinting patterns have not been studied. Here, we first established parthenogenetic epiblast stem cells (pEpiSCs) from 7.5 dpc parthenogenetic implantation embryos and compared the expression patterns and DNA methylation status of the representative imprinted genes with biparental EpiSCs. We found that there were no striking differences between pEpiSCs and biparental EpiSCs with respect to morphology, pluripotency gene expression, and differentiation potential, but there were differences in the expression and DNA methylation status of imprinted genes (H19, Igf2, Peg1, and Peg3). Moreover, pEpiSCs displayed a different DNA methylation pattern compared with that of parthenogenetic neural stem cells (pNSCs), which showed a typical bimaternal imprinting pattern. These results suggest that both naive pluripotent stem cells and primed pluripotent stem cells have an unstable imprinting status.