SELF-PATTERNING OF HUMAN STEM CELLS INTO POST-IMPLANTATION LINEAGES

Investigating human development is a significant scientific challenge due to the technical and ethical limitations of working with bona fide embryo samples. In the face of these difficulties, stem cells have been applied to experimentally model inaccessible stages of human development in vitro. Here we show that human pluripotent stem cells can be triggered to self-organise into three-dimensional structures that recapitulate the spatiotemporal events of early human post-implantation embryonic development. We report single-cell transcriptomics that confirms differentiation into diverse cell states of the native gastrulating human embryo, including signatures of post-implantation epiblast, amniotic ectoderm, primitive streak, mesoderm, and hypoblast, as well as pre-patterning of non-neural ectoderm and yolk sac. Collectively, our system captures key features of human embryonic development spanning from Carnegie-stage13 (CS) 4 to CS7, providing a reproducible, tractable, and flexible experimental platform to understand the basic cellular and molecular mechanisms that underlie human development, and a high-throughput platform to dissect developmental disorders and congenital pathologies. Overall design: Human pluripotent cells spontaneously differentiated in 3D culture platform into structures called "human extraembryoid (hEE)". The hEEs collected for single cell RNA sequencing either at Day 4 or Day 6 in vitro