Purpose of Review Vascular endothelial stem cell (VESC) and progenitor cell are emerging as local resident regulators of vascular endothelial repair and replacement in mammalian subjects. However, widely recognized and accepted standard measures of stem cell function have yet to be published and, thus, we summarize some recent evidence that VESCs demonstrate stem cell properties in the process of endothelial cell (EC) lineage emergence, repair, and regeneration.

Recent Findings Some rare resident ECs have been identified that are quiescent and reside within blood vessels but are activated and proliferate in response to injury. Transcriptome analyses of these ECs at a single cell level are providing new insights into VESC identity, including tissue specific EC heterogeneity.

Summary Blood vessels and circulating blood contain rare immature ECs that display stem cell potential. Continuous efforts to define their precise location, origin, surface marker, and molecular signatures would enhance current approaches for purification of cells that would enable us to build new vessels for regenerative medicine.