Mesenchymal progenitor cells in perivascular niches: forerunners of mesenchymal stem cells and players in tissue scarring and regeneration

Abstract

The walls of all embryonic, foetal, and adult blood vessels contain mesodermal progenitors, distributed as pericytes in capillaries and micro vessels, and fibroblastic cells in the tunica adventitia of larger veins and arteries. Following dissociation, selection by flow cytometry, and culture, those perivascular cells turn into bona fide mesenchymal stem cells of which they possess all attributes. In vivo, the adventitial cellular niche supports several spatially-organized subsets of mesodermal progenitors biased toward either osteo-, adipo-, or fibrogenesis, and dominated by more primitive, multi-lineage stem-like cells. Experiments in reporter mice have shown that perivascular progenitor cells play roles in tissue scarring, turnover, and regeneration, but also in pathologic fibrosis and vascular remodelling. This review briefly summarizes the phenotypes, anatomical distribution, and developmental capacities of perivascular mesenchymal progenitor cells, underlining the potential interest thereof for cell therapies, tissue engineering, and disease prediction.