BETHESDA, Md., Feb. 12 (UPI) -- A type of adult stem cell found in the blood could repair damaged blood vessels and help stave off heart disease, National Institutes of Health researchers said Wednesday.
The findings could lead to new therapies to prevent heart disease and stroke and a new way of measuring a person's risk of developing those conditions, Dr. Toren Finkel, the study's principal investigator and chief of the cardiovascular branch at the National Heart, Lung, and Blood Institute in Bethesda, told United Press International.
Finkel's team looked at levels of endothelial progenitor cells, a type of adult stem cell made in the bone marrow and released into the blood, in 45 men with an average age of 50 who did not have cardiovascular disease.
Men with lower levels of the stem cells had a higher risk of developing cardiovascular disease, the researchers report in Thursday's New England Journal of Medicine.
Risk of cardiovascular disease, which can lead to a heart attack or stroke, was determined by assessing the number of factors known to play a role in causing the condition -- including smoking, obesity, physical activity, high cholesterol levels and high blood pressure -- each man had.
Men with lower levels of the stem cells had blood vessels that were less likely to dilate or function properly.
In addition, stem cells taken from men with the highest risk of developing cardiovascular disease aged faster in a test tube, suggesting increased risk factor factors inhibited the cell's repair abilities.
The findings suggest "these cells normally function to repair the blood vessel wall ... and when you don't have enough of these cells you could be in trouble," Finkel said.
It is unclear why men with the highest risk of cardiovascular disease -- and thus the greatest need for repairing damaged blood vessels -- would have lower levels of the stem cells. It could be the "same things that damage the blood vessel walls also damage these cells," Finkel said.
Another possibility is the body can only produce a fixed amount of the cells "so the more that you require for repair, the less you have in circulation," he added.
The study is "a very important observation" and "sheds a lot of light on the way the body repairs itself," Dr. Robert Bonow, chief of cardiology at the Northwestern University Medical School in Chicago and president of the American Heart Association, told UPI.
The findings demonstrate that "when you have a lot of risk factors for blood vessel disease and heart disease the body's ability to repair itself is impaired," Bonow said. The results also suggest "very interesting possibilities for future therapy," he said.
Finkel's team is looking at whether replenishing these cells or stimulating the body to produce more of them could prevent cardiovascular disease.
Other studies are looking at whether exercise or other things known to improve cardiovascular health improve levels of these stem cells, Arshed Quyyumi, a co-author of the study and a professor of medicine at Emory University in Atlanta, told UPI.
Quyyumi noted a class of drugs called statins, used to lower high cholesterol levels and reduce the risk of developing heart disease, have been shown to triple the levels of these stem cells.
"It's possible that much of the benefit (of statins) is mediated through improving levels of these cells," he said.
(Reported by Steve Mitchell, UPI Medical Correspondent, in Washington.)