Capture of Mouse and Human Stem Cells with Features of Formative Pluripotency

Pluripotent cells emerge as a naive founder populationin the blastocyst, acquire capacity for germline and soma formation, and then undergo lineage priming. Mouse embryonic stem cells (ESCs) and epiblast-derived stem cells (EpiSCs) represent the initial naive and final primed phases of pluripotency, respectively. Here, we investigate the intermediate formative stage. Using minimal exposure to specification cues, we derive stem cells from formative mouse epiblast. Unlike ESCs or EpiSCs, formative stem(FS) cells respond directly to germ cell induction. They colonize somatic tissues and germline in chimeras. Whole-transcriptome analyses show similarity to pre-gastrulation formative epiblast. Signal responsiveness and chromatin accessibility features reflect lineage capacitation. Furthermore, FS cells show distinct transcription factor dependencies, relying critically on Otx2. Finally, FS cell culture conditions applied to human naive cells or embryos support expansion of similar stem cells, consistent with a conserved staging post on the trajectory of mammalian pluripotency.

Automated summary

The study reveals that formative stem (FS) cells, a novel type of stem cells, can directly respond to germ cell induction and differentiate into somatic tissues and germline in chimeras. Unlike embryonic stem cells (ESCs) or epiblast-derived stem cells (EpiSCs), FS cells exhibit distinct transcription factor dependencies, primarily relying on Otx2.