Researchers find key mechanism leading to vascular calcification - 'hardening of the arteries, valves or plaque'

A University of Miami Miller School of Medicine research team has uncovered a key mechanism in the development of vascular calcification, or hardening of the arteries, valves or plaque - a disorder that affects millions of people.

"We have identified a clear linkage between a specific microRNA molecule, which is naturally produced by the body, and vascular calcification," said Lina A. Shehadeh, Ph.D., assistant professor of medicine in the Cardiovascular Division and investigator in the Miller School's Interdisciplinary Stem Cell Institute. "As people age, the body produces less of this microRNA and calcification of the blood vessels increases."

That groundbreaking finding could have significant clinical implications in potentially preventing or reversing hardening of the arteries and valves, according to Shehadeh, who was the lead author on a study published in the prestigious journal Cardiovascular Research. "MicroRNAs can easily be injected into the body," she said. "While further laboratory studies and clinical trials are needed, we can hypothesize that raising the levels of this microRNA could slow or even reverse the process of vascular calcification."

About 787,000 Americans died of cardiovascular disease in 2011, according to the most recent statistics from the American Heart Association, which estimates that more than 85 million Americans are living with some form of cardiovascular disease or the after-effects of stroke. Vascular calcification is not only prevalent in cardiovascular disease patients, but also in patients with Type II diabetes and chronic kidney disease as well as in the aged population.

Shehadeh's three-year research project - which focused on how a microRNA regulates calcification of bone marrow-derived mesenchymal stem cells and aortic smooth muscle cells - was funded by grants from the National Institute on Aging, the State of Florida, the Florida Heart Research Institute, and the American Federation for Aging Research.

"Artery walls consist mainly of smooth muscle cells, but over time, the smooth muscle cells can begin growing abnormally," she said. "When they start dividing and migrating, plaques form, making it more difficult for blood to flow through them. Those blockages can cause clots to form, further blocking blood flow, and pieces of plaque can actually break off and move to smaller vessels, blocking them entirely."

Shehadeh added that people who have high cholesterol or are overweight are at high risk for vascular calcification, and that risk increases with age. "While certain medicines can slow the process, currently there are no treatments to reverse the calcification once it has occurred," she said.

"The microRNA we identified regulates other molecules, such as Insulin Growth Factor II, that have been associated with age and calcification," Shehadeh said. "Using various genetic animal models, we are planning the next studies to learn more about this key process. Importantly, we are active in establishing microRNA delivery methods that can eventually be used in humans."