Fate and State Transitions during Human Blood Vessel Organoid Development: Time Course

Human blood vessel organoids (hBVOs) derived from human pluripotent stem cells have emerged as a novel system to understand human vascular development, model disorders, and develop regenerative therapies. However, it was unclear which molecular states constitute hBVOs and how cells differentiate and self-organize within hBVOs in vitro and after transplantation. Here we reconstruct hBVO development over a time course using single-cell transcriptomics. Data includes day 3, 4, 5, 6, 7, 14 and 21 of hBVO differentiation, as well as 2 months post-transplantation of 14-day hBVOs into immunocompromised mice. We observe progenitor states that bifurcate into endothelial and mural fates, and find that hBVOs do not acquire definitive arterio-venous endothelial identities in vitro. Chromatin accessibility profiling at days 3, 4 and 7 identifies gene regulatory network (GRN) features associated with endothelial and mural fate decisions. Transcriptome-coupled lineage recording reveals multipotent progenitor states within BVOs. These data provide the first comprehensive cell state atlas of BVO development.