Circulating Stem Cells Point to Cardiovascular Risk

A recent study found that the level of circulating endothelial progenitor cells, stem cells made in the bone marrow, might be used as an indicator of cardiovascular disease risk. The study appeared in the February 13, 2003, issue of The New England Journal of Medicine.

Researchers from the National Heart, Lung, and Blood Institute (NHLBI, Bethesda, MD, USA) measured the number of colony-forming units of endothelial progenitor cells in peripheral-blood samples from 45 men who were close to 50 years of age. The subjects had various degrees of cardiovascular risk but no history of cardiovascular disease. Endothelium-dependent and endothelium-independent function was assessed by high-resolution ultrasonography of the brachial artery.

They found a strong correlation between the number of circulating endothelial progenitor cells and the subjects' combined Framingham cardiovascular risk factor score. Cardiovascular disease risk was higher in those subjects with fewer endothelial progenitor cells. Measurement of flow-mediated brachial-artery reactivity also revealed a significant relation between endothelial function and the number of progenitor cells. In addition, endothelial progenitor cells from subjects at high risk for cardiovascular events had higher rates of in vitro senescence than cells from subjects at low risk.

"We believe that these endothelial progenitor cells patch damaged sites in blood vessel walls, explained senior author Dr. Toren Finkel, chief of the cardiology branch at the National Heart, Lung, and Blood Institute "When the cells start to run out, cardiovascular disease worsens. We do not yet know what causes their depletion but it may be related to the fact that the risk of cardiovascular disease increases as people age. For instance, the cells may be used up repairing damage done by other risk factors or those risk factors could directly affect the survival of the endothelial cells themselves.”




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