Identification of blood vascular endothelial stem cells by the expression of protein C receptor.

Vascular growth and remodeling are dependent on the generation of new endothelial cells from stem cells and the involvement of perivascular cells to maintain vessel integrity and function. The existence and cellular identity of vascular endothelial stem cells (VESCs) remain unclear. The perivascular pericytes in adult tissues are thought to arise from the recruitment and differentiation of mesenchymal progenitors during early development. In this study, we identified Protein C receptor-expressing (Procr ⁺ ) endothelial cells as VESCs in multiple tissues. Procr ⁺ VESCs exhibit robust clonogenicity in culture, high vessel reconstitution efficiency in transplantation, long-term clonal expansion in lineage tracing, and EndMT characteristics. Moreover, Procr ⁺ VESCs are bipotent, giving rise to de novo formation of endothelial cells and pericytes. This represents a novel origin of pericytes in adult angiogenesis, reshaping our understanding of blood vessel development and homeostatic process. Our study may also provide a more precise therapeutic target to inhibit pathological angiogenesis and tumor growth.