Circulating vascular progenitor cells contribute to vascular repair, remodeling, and lesion formation.

Exuberant accumulation of smooth muscle cells (SMCs) plays a principal role in the pathogenesis of vascular diseases. It has been assumed that SMCs derived from the adjacent medial layer migrate, proliferate, and synthesize extracellular matrix. Although much effort has been devoted to understanding the molecular pathways regulating migration and proliferation of medial SMCs, no effective therapy to prevent occlusive vascular remodeling has been established. It was recently reported that bone marrow cells substantially contribute to the pathogenesis of vascular diseases, in models of postangioplasty restenosis, graft vasculopathy, and hyperlipidemia-induced atherosclerosis. It was suggested that bone marrow cells may have the potential to give rise to vascular progenitor cells that home in on the damaged vessels and differentiate them into smooth muscle cells or endothelial cells, thereby contributing to vascular repair, remodeling, and lesion formation. The present findings may provide the basis for the development of new therapeutic strategies for vascular diseases, targeting mobilization, homing, differentiation, and proliferation of circulating vascular progenitor cells.