Early Risks to Heart Health
By Quinn Eastman
Burning the candle at both ends. Spreading yourself too thin.
A number of old adages remind us that energy and endurance are finite resources.
Emory cardiologists recently showed that cells that repair our blood vessels and other tissues also behave like limited resources, and that stress on the circulatory system early in life may deplete its regenerative capacity later.
Professor of Medicine Arshed Quyyumi and colleagues at Emory's Clinical Cardiovascular Research Institute have been studying circulating progenitor cells, or CPCs, for many years.
These rare cells in the blood are key indicators of regenerative capacity. They're capable of becoming endothelial cells, which line blood vessels, as well as red and white blood cells. When harvested from the bone marrow and delivered in sufficient numbers, they improve the capacity of the heart to repair itself after a heart attack.
CPCs also seem to be an indicator of cardiovascular health. People with more cardiovascular risk factors, such as diabetes, high blood pressure, or high cholesterol, tend to have lower numbers of these cells as they age. And heart disease patients who have lower numbers of CPCs have a much higher risk of dying over the next few years.
In studies that included younger people, Quyyumi's team found some contradictory results: levels of these cells actually tended to go up with cardiovascular risk. That makes sense, because physical or mental stress stimulate CPCs to emerge from the bone marrow.
In a paper published in Circulation Research in 2016, the Emory team wove these strands together by combining two groups of study participants: mostly healthy university employees from Emory and Georgia Tech with a large database of hospitalized patients undergoing cardiac catheterization.
For people younger than 40, risk factors were associated with increased CPC counts, but for older people in their 60s, risk factors and cardiovascular disease were associated with lower progenitor cell counts. This suggests that time, by itself, does not deplete CPCs, but unhealthy living does.
"Circulating progenitor cell levels do not decline with healthy aging," the authors concluded. "Risk factor exposure at a younger age stimulates progenitor cell mobilization, whereas continued exposure is associated with lower progenitor cell levels in later life."