In vivo haematopoietic cell production by bone marrow-derived hemogenic endothelium. In vivo haematopoietic cell production by bone marrow-derived hemogenic endothelium

By tracing the VE-cadherin expression in the newborn bone marrow hematopoietic LSK (lineage minus/Sca-positive/Kit-positive) cells, we demonstrated that the late foetal/newborn BM hemogenic endothelial cells produce a small cohort of hematopoietic stem and progenitor cells (HSPCs) capable of circulating and colonizing the secondary haematopoietic organs. Phenotypic and functional analyses disclosed that BM endothelium-derived HSPCs are mainly Multipotent Progenitors (MPPs) and a few Hematopoietic Stem Cells. We used microarrays to detail the global programme of gene expression underlying the endothelial origin of LSK cells in the newborn bone marrow. Overall design: Six samples were analyzed including YFP positive cells (3 replicates) and YFP negative cells (3 replicates). We used the tamoxifen inducible Tg(Cdh5-Cre/ERT2) mice crossed to Rosa 26 YFP mice. Tamoxifen induction was performed at 1, 2 and 3 days after birth. At day 26 after day 1 induction, LSK cells were FACS-sorted and separated into YFP-positive and YFP-negative cells. YFP reports the expression of VE-Cadherin