VCAM-1+ macrophages usher hematopoietic stem and progenitor cell to vascular niche “hotspots”

In mammals, evidence suggests that hematopoietic stem and progenitor cells (HSPCs) arise in the aorta-gonad-mesonephros (AGM) region (1), migrate to the liver (2) and then to the bone marrow (BM) where definitive hematopoiesis is established shortly after birth and remains sustained during the rest of the mammal’s life.