Involvement of progenitor cells in vascular repair

Whereas the genesis of an arterial lesion is thought to be the result of migration and proliferation of vascular cells, recent insights into the biology of progenitor cells now question this concept. Specifically, endothelial and smooth muscle cells appear to be derived from multiple sources such as circulating stem and progenitor cells, as well as tissue-resident progenitor cell populations. These cells may engraft at sites of vascular injury and play an integral role in vascular repair. In this review, experimental data from in vitro studies, animal models, and scattered human observations are reviewed in the context of emerging hypotheses regarding the response to vascular injury.