Trophectoderm Potency is Retained Exclusively in Human Naïve Cells

Classical mouse embryology has established a sequence of lineage bifurcations underpinning early mammalian development. Consistent with this paradigm, mouse embryonic stem cells have lost the capacity to generate extraembryonic trophectoderm. We show here, however, that human naive epiblast stem cells readily produce this lineage. Inhibition of ERK signalling, fundamental to naive cell propagation, is unexpectedly instrumental in trophectoderm induction. Transcriptome analyses authenticate trophoblast fate and expose a trajectory via reversion to inner cell mass (ICM). Nodal inhibition enhances differentiation and BMP signalling is not engaged. Strikingly, after formative transition primed stem cells cannot make trophectoderm but respond to BMP and form amnion. Gene perturbations in naive cells reveal that YAP and TFAP2C promote trophectoderm as in mouse, while NANOG suppresses distinctively in human. Finally, ICMs from expanded human blastocysts efficiently regenerate trophectoderm. Thus in human, retained trophectoderm potential is an integral feature of emergent pluripotency that confers higher regulative plasticity.