Vascular stem cells: a new concept in the pathogenesis of atherosclerosis and interventions for coronary heart disease.

Vascular stem cells are undifferentiated, oligopotent progenitor cells that are capable of giving rise to mature, functional cells in the vascular wall. Several types of vascular progenitor cells have been identified and characterized from embryonic and adult tissues, including progenitors with the potential to differentiate into endothelial and smooth muscle cells. The progenitors for endothelial and smooth muscle cells reside in atherosclerotic or restenotic lesions and circulate in the bloodstream. These stem cells may malfunction under the influence of the risk factors for atherosclerosis, as well as by medical interventions. The biological activities of these stem cells contribute to the regeneration, repair and remodeling of arterial walls injured by atherosclerosis. Hypercholesterolemia, inflammation, mechanical stress and genetic defects may interact in regulating the vascular stem cell response to atherogenic stimulation. Stem cell production, potency, growth and differentiation may decline as people age. Clarifying the cellular and molecular pathways that govern stem cell growth, differentiation and apoptosis should help clinical scientists to understand the pathogenesis of atherosclerosis and to develop novel therapeutic strategies for coronary heart disease. Recent clinical trials demonstrate encouraging outcomes of stem cell therapies.