If the head counts of these "stem" cells are low, it "might be an indicator of who's going to run into trouble and who isn't," said study co-author Dr. Toren Finkel, chief of the cardiovascular branch at the National Institutes of Health.
The next step is to figure out whether boosting the number of the handymen cells would help sick people prevent disease, he said.
But Finkel acknowledged that scientists disagree about the exact role of the cells, known as endothelial, which live in the lining of blood vessels.
"Most of the work has suggested that the role is to grow new blood vessels, not repair them," he said. "We have a slightly different take. We believe their primary function is to repair your own blood vessels, but they can help form new ones too."
In conjunction with Emory University Hospital in Atlanta, Finkel and colleagues examined 45 healthy men aged 21 and older. They report their findings in the Feb. 13 issue of the New England Journal of Medicine.
The blood vessels in the worst shape belonged to the men with the lowest numbers of endothelial stem cells, which are primed to become full-fledged endothelial cells. Those vessels were less likely to open properly, suggesting that they could be prone to clogs in the future.
"If you had higher levels [of endothelial cells], your blood vessels were able to function properly," Finkel said. "We can't prove that [those things] are related, but there was a tight correlation."
The researchers aren't sure of the exact meaning of the apparent link between the cell count and the condition of the blood vessels. Heart disease could exhaust the cells, or loss of cells could contribute to heart disease, Finkel said.
But the cell counts, which come from a simple blood test, could turn into a helpful diagnostic test, he added.
"We're particularly interested in looking at people who don't have classical risk factors," such as those with high blood pressure, smoking, and diabetes, he said. "There are probably risk factors we don't know anything about."
Dr. Steve Sidney, associate director for clinical research for Kaiser Permanente Northern California, a health plan, said the study breaks new ground by examining what can be done to fix blood vessels instead of preventing damage in the first place.
"It's early work, but the concept itself is very intriguing and potentially promising," he said.
It may be possible to inject the endothelial cells into the body or stimulate bone marrow to produce more of them, he added.
More than 1.1 million Americans suffer a heart attack every year, and 44 percent die, according to the National Heart, Lung and Blood Institute. For more information about heart attacks and other cardiovascular ailments, try the American Heart Association or the National Heart, Lung and Blood Institute.