PDGFRß+ cells play a dual role as hematopoietic precursors and niche cells during mouse ontogeny

Hematopoietic stem cell (HSC) generation in the aorta-gonads-mesonephros region requires HSC specification signals from the surrounding microenvironment. In zebrafish, PDGF-B/PDGFRß signaling controls hematopoietic stem/progenitor cell (HSPC) generation and is required in the HSC specification niche. Little is known about murine HSPC specification in vivo and whether PDGF-B/PDGFRß is involved. Here we show that PDGFRß is expressed in distinct perivascular stromal cell layers surrounding the mid-gestation dorsal aorta, and its deletion impairs hematopoiesis. We demonstrate that PDGFRß+ cells play a dual role in murine hematopoiesis. They act in the aortic niche to support HSPCs, and in addition, PDGFRß+ embryonic precursors give rise to a subset of HSPCs that persist into adulthood. These findings provide crucial information for the controlled production of these clinically important cells in vitro. Overall design: A C57/BL6 litter was analyzed (embryos pulled together in one sample)