Blood: Single-cell sequencing reveals developmental trajectory from endothelial cells to hematopoietic stem cell precursors

Hematopoietic stem cells and progenitor cells (HSPCs) in bone marrow are derived from a small group of hematal endothelial cells (HE) in the aorta of mammalian embryosHe cells undergo transformation (EHT) from endothelial cells to hematopoietic cells before being implanted in the fetal liver, causing HSPCs to accumulate in the arteries (IAC)To examine cell and molecular transformation between endothelial cells (E), HE and IAC cells, as well as the heterogeneity of HSPCs in IACs, the researchers analyzed the chromatin sequencing (scATAC-Seq) through single-cell RNA sequencing (scRNA-Seq) and single-cell transposhestase The continuous development trajectory from E-to HE cells to IAC cells, as well as the identifiable intermediate stages, was determined in 37,000 cells in the embryonic tail artery (DA), umbilical cord (U), egg yolk (V) of the embryo from 9.5 days (E9.5) to E11.5the nearest intermediate stage of HE, known to researchers as pre-HE, which is characterized by increased chromatin rich in SOX, FOX, GATA, and SMAD moldsA developmental bottleneck distinguishes pre-HE and HE, and runX1 levels regulate the efficiency of pre-HE's conversion to HEAt bottlenecks, a distant candidate Runx1 enhancer in the pre-HE cell exhibited a higher chromatin and specificitydifferent development almost trajectories within IAC cells led to two groups of CD45-HSPCs; first, the lymphocyte-biased progenitor cells, followed by the hematopoietic stem cell (pre-HSCs) precursorin general, the multi-group single-cell map in this study greatly expands our understanding of the occurrence of HSC precursors