Identification of vascular endothelial stem cells (Takakura Lab, in Cell Stem Cell)

The generation of new blood vessels via angiogenesis is critical for meeting tissue oxygen demands. A role for adult stem cells in this process remains unclear. Here we identified CD157 (bst1, bone-marrow stromal antigen-1) as a marker of tissue resident vascular endothelial stem cells (VESC) in large arteries and veins of numerous mouse organs. Single CD157+ VESC form colonies in vitro and generate donor-derived portal vein, sinusoids and central vein endothelial cells upon transplantation in the liver. In response to injury, VESCs expand and regenerate entire vasculature structures, supporting the existence of an endothelial hierarchy within blood vessels. Genetic lineage tracing revealed VESC maintain large vessels and sinusoids in the normal liver for more than a year and transplantation of VESCs rescued bleeding phenotypes in a mouse model of hemophilia. Our findings establish that tissue resident VESC displaying self-renewal capacity and that vascular regeneration potential exists in peripheral blood vessels.