Human blastoids model blastocyst development and implantation [Bulk RNA-seq]

Shortly after fertilization, human embryos implant into the uterus. This requires the formation of a blastocyst consisting of a sphere encircling a cavity lodging the embryo proper. Appropriate stem cells can form a blastocyst model, which we termed blastoid. Here we show that naive human pluripotent stem cells (hPSCs) triply inhibited for the Hippo, TGF-β, and ERK pathways consistently and efficiently (>70%) form blastoids that generate transcriptional pre-implantation analogs of the three founding lineages (trophoblast, epiblast, primitive endoderm; >97%) according to the  sequence and pace of blastocyst development. Blastoids spontaneously form an axis marked by the maturation of the polar region, which acquires the potential to specifically attach to hormonally stimulated endometrial cells, as during in utero implantation. Such human blastoids are scalable, versatile, and ethical models to explore human implantation and development. 61 samples