Lineage-tracing hematopoietic stem cell origins in vivo to efficiently make human HLF plus HOXA plus hematopoietic from pluripotent stem cells

The developmental origin of blood -forming hematopoietic stem cells (HSCs) is a longstanding question. Here, our non-invasive genetic lineage tracing in mouse embryos pinpoints that artery endothelial generate HSCs. Arteries are transiently competent to generate HSCs for 2.5 days (similar to E8.5-E11) but subsequently cease, delimiting a narrow time frame for HSC formation in vivo . Guided by the arterial origins blood, we efficiently and rapidly differentiate human pluripotent stem cells (hPSCs) into posterior primitive streak, lateral mesoderm, artery endothelium, hemogenic endothelium, and >90% pure hematopoietic genitors within 10 days. hPSC-derived hematopoietic progenitors generate T, B, NK, erythroid, and myeloid cells in vitro and, critically, express hallmark HSC transcription factors HLF and HOXA5-HOXA10 , which previously challenging to upregulate. We differentiated hPSCs into highly enriched HLF + HOXA + hematopoietic progenitors with near-stoichiometric efficiency by blocking formation of unwanted lineages at each ferentiation step. hPSC-derived HLF + HOXA + hematopoietic progenitors could avail both basic research cellular therapies.