Derivation of formative-like pluripotent stem cells from mammalian embryos [ChIP-Seq]

Two phases of pluripotency, naïve and primed, have been captured in vitro and studied in details1. A third formative phase was recently proposed to exist between naïve and primed phases2. Formative pluripotency entails permissiveness for direct primordial germ cell (PGC) induction and competence for blastocyst chimeras, and is characterized by transcriptional and epigenetic features intermediate of naïve and primed pluripotency. To date, however, stable pluripotent stem cells (PSCs) harboring formative features haven't been derived from early mammalian embryos. Here we develop a method which enabled the derivation and culture of stable formative-like embryonic stem cells (ESCs) from mouse blastocysts. Formative-like mouse ESCs share molecular features characteristic of early post-implantation epiblasts and are competent for PGC-like cell induction and blastocyst chimera formation. The same culture also supported the derivation of ESCs and transgene-free induced pluripotent stem cells (iPSCs) from horse blastocysts and fibroblasts, respectively. Horse ESCs/iPSCs transcriptionally resembled mouse formative cells, and could also be directly induced into PGC-like cells. Formative-like horse iPSCs could efficiently chimerize horse, mouse, goat, sheep and pig embryos. Stable formative-like PSCs will be invaluable for studying mammalian pluripotency, and our method may be broadly applicable for the derivation of PGC and chimera competent PSCs from other mammalian species. Overall design: We collected Embryonic cells form mouse and horse.