Establishment of mouse primitive endoderm stem cell lines [scRNA-Seq II]

The mammalian blastocyst consists of three distinct cell types: epiblast, trophoblast (TB), and primitive endoderm (PrE). Although embryonic stem cells (ESCs) and trophoblast stem cells (TSCs) retain the functional properties of Epi and TB, the currently available extraembryonic endoderm cells (XENC) do not fully recapitulate the developmental potential of PrE. Here we report derivation of primitive endoderm stem cells (PrESCs) in mice. PrESCs express both PrE and pluripotency marker genes like founder PrE. These cells are efficiently incorporated into PrE upon blastocyst injection, generate functionally competent PrE-derived tissues, and support fetal development of PrE-depleted blastocysts in chimeras. Establishment of PrESCs therefore represents a significant step-forward in elucidating the mechanisms for PrE specification and subsequent pre- and post-implantation development. Overall design: We investigated the differentiation capability of PrESCs by using a modified blastoid self-organization method, in which PrESCs, ESCs and TSCs were sequentially assembled to form ETP complexes (ETP). In this condition, respective stem cells established uniform contacts in ETPs by day3. We then assessed differentiation status of respective stem cells by scRNA-seq analysis for respective stem cells and day3 and day6 ETPs.