Atherosclerosis is a buildup of deposits on the inner walls of arteries. By narrowing the arteries, impairing their ability to function, and obstructing blood flow, it is a significant contributor to most types of cardiovascular disease.

It is widely believed that injury to endothelial cells (which comprise the endothelium, the innermost layer of cells in blood vessels) stimulates the development of atherosclerotic plaques. Multiple factors including smoking, high blood pressure , and diabetes combine to cause this injury. Several studies have demonstrated that endothelial cell function can predict the risk of cardiovascular events.

Like most cells in the body, endothelial cells come from less developed predecessor cells that travel through blood vessels and replace damaged or lost endothelial cells. Researchers from the National Heart, Lung and Blood Institute and Emory University Hospital in Atlanta speculated these so called endothelial progenitor cells might repair and/or replace damaged endothelial cells. If so, they reasoned, levels of these cells in the bloodstream should be related to endothelial function and cardiovascular risk.

The scientists found that in healthy men, such an association did in fact exist.

About the Study

The researchers enrolled 45 healthy men, with an average age of 50 years, some of whom had conventional cardiovascular disease risk factors and others of whom did not. The study participants did not take any medications, including vitamins, during the course of the study.

Using a well established risk assessment tool, the researchers calculated each participant’s risk for a cardiovascular event based on conventional risk factors, such as hypertension, smoking, high cholesterol , and diabetes. They then collected a blood sample from each volunteer, from which they measured the level of endothelial progenitor cells. Finally, they used the ability of a sample artery to dilate to assess how well the endothelial cells were functioning.

The levels and activity of the endothelial progenitor cells were compared to cardiovascular risk factors and endothelial function.

The Findings

The levels of circulating endothelial progenitor cells were significantly reduced in participants with elevated serum cholesterol levels, hypertension, and diabetes. Study participants with the highest cardiovascular risk had the lowest levels of endothelial progenitor cells.

The blood vessels of participants with the highest levels of endothelial progenitor cells seemed to work the best. When participants were divided into three groups based on endothelial function, the group with the best functioning endothelial cells had endothelial progenitor cell counts that were three times higher those with the worst functioning cells.

Interestingly, the level of circulating endothelial progenitor cells was a significantly better at predicting endothelial function than the Framingham risk score.

How Does This Affect You?

This study suggests that circulating endothelial progenitor cells may be a more accurate predictor of endothelial function, and thus cardiovascular risk, than conventional risk factors. The reasons for this relationship are not known. The researchers suggest that since endothelial progenitor cells play a role in the repair or replacement of damaged endothelial cells, over time their levels may become depleted or exhausted. With additional research, endothelial progenitor cell levels could become a standard way to measure cardiovascular disease risk in the future.

This study, however, has far broader implications. Regenerative medicine, a highly active area of research, is based on the concept that damaged or lost tissue can be replaced by younger, healthier cells. By harnessing these cells from within the body, harvesting them from a donor, or growing them in a laboratory, the idea is to literally make the tissue “as good as new”. This research on progenitor endothelial cells has contributed significantly to our understanding of regenerative cells in one part of the body, and it may lead to new and innovative methods for treating the number one killer of Americans: atherosclerotic diseases.