Smooth muscle progenitor cells in vascular disease.

Vascular smooth muscle cells have long been described as phenotypically diverse, with some populations possessing the potential for monoclonal expansion within the adult vessel wall. Recent experimental and human data suggest a potential role in atherosclerotic plaque, transplant arteriopathy, and angiogenesis biology for putative smooth muscle progenitor cells in the circulation, adult tissues, and the perivascular adventitia. The location, mobilization, and function of such progenitors is still poorly understood, but may include reparative or alternatively proliferative consequences for plaque development and progression. These observations provide a platform for re-evaluation of smooth muscle cell heterogeneity and progenitor biology in atherosclerosis, with implications for diagnosis and therapy of vascular disease.