3D-cultured blastoids model human embryogenesis from pre-implantation to early gastrulation stages

Naïve human pluripotent stem cells have the remarkable ability to self-organize into blastocyst-like structures (“blastoids”) that model lineage segregation in the pre-implantation embryo. However, the extent to which blastoids can recapitulate defining features of human post-implantation development remains unexplored. Here, we report that blastoids cultured on thick 3D extracellular matrices capture hallmarks of early post-implantation development, including epiblast lumenogenesis, rapid expansion and diversification of trophoblast lineages, and robust invasion of extravillous trophoblast cells by day 14. Extended blastoid culture results in the localized activation of primitive streak marker TBXT and the emergence of embryonic germ layers by day 21. We also show that modulation of WNT signaling alters the balance between epiblast and trophoblast fates in post-implantation blastoids. This work demonstrates that 3D-cultured blastoids offer a continuous and integrated in vitro model system of human embryonic and extraembryonic development from pre-implantation to early gastrulation stages. Overall design: Single cell RNA seq profiles of blastoids generated from 5i/L/A naïve hPSCs at preimplantaiton (7 days) and post implantation (14 and 21 days)