new blood forming vessels are produced by differentiation of mesodermal precursor cells to angioblasts that become endothelial cells (ecs) which in turn give rise to primitive capillary network. human cord blood (hcb) contains large subsets of mononuclear cells (mncs) that can be differentiated into endothelial-like cells in vitro. human mononuclear progenitor cells were purified from fresh umb...