Endothelial repair by stem and progenitor cells

The integrity of the endothelial barrier is required to maintain vascular homeostasis and fluid balance between the circulatory system and surrounding tissues and to prevent the development of vascular disease. However, the origin of the newly developed endothelial cells is still controversial. Stem and progenitor cells have the potential to differentiate into endothelial cell lines and stimulate vascular regeneration in a paracrine/autocrine fashion. The one source of new endothelial cells was believed to come from the bone marrow, which was challenged by the recent findings. By administration of new techniques, including genetic cell lineage tracing and single cell RNA sequencing, more solid data were obtained that support the concept of stem/progenitor cells for regenerating damaged endothelium. Specifically, it was found that tissue resident endothelial progenitors located in the vessel wall were crucial for endothelial repair. In this review, we summarized the latest advances in stem and progenitor cell research in endothelial regeneration through findings from animal models and discussed clinical data to indicate the future direction of stem cell therapy. [Display omitted] •Stem and progenitor cells have the potential to differentiate into endothelial cells and stimulate vascular regeneration.•CD34+ cells from the bone marrow are not endothelial progenitor cells and more prone to differentiate into inflammatory cells.•Tissue resident endothelial progenitors located in the vessel wall are crucial for endothelial repair.•The cell heterogeneity may be one of the reasons for unsatisfactory results of clinical therapy using CD34+ cells.