High blood-sugar levels may harden heart valves

Rice University bioengineers have found new evidence of a possible link between diabetes and the hardening of heart valves.

A Rice lab, in collaboration with the University of Texas (UT) Medical School at Houston, discovered that the interstitial cells that turn raw materials into heart valves need just the right amount of nutrients for proper metabolic function.

The surprise was that feeding them too much glucose, a sugar, slowed the cells down.

Diabetes is a metabolic disease characterized by high blood-sugar levels over a long period; a 2006 study of atherosclerosis by University of Washington researchers found a correlation between diabetes and aortic-valve calcification.

In the new work by the lab of Jane Grande-Allen of Rices bioengineering department, recently ranked No. 5 in the nation by U.S. News & World Report, researchers have directly seen the effect of high blood-sugar levels on heart-valve cell metabolism for the first time. The study appears this month in the Journal of the Royal Society Interface.

The most significant result of the study is that high glucose concentration can actually be detrimental to the aortic-valve cells and their behavior in interacting with the extracellular matrix, said lead author Peter Kamel, who carried out the experiments as a Rice undergraduate. He is in his third year at Baylor College of Medicine, where he is completing a dual-degree program offered by the neighboring Houston institutions.

Weve seen in a variety of other cell types, like cells in the kidney, the retina and nerves, that high glucose concentrations can directly damage those cells and their activities, he said. That results in patients with diabetes having problems with vision and with their nerves and kidneys as well.

The results that high glucose concentration can also cause pathologic remodeling by the aortic-valve cells could suggest that diabetes is also directly a cause of aortic-valve disease, he said.

Grande-Allens lab studies the biomechanics of heart valves, particularly their calcification, or hardening, a condition that lessens blood flow to the heart. In the new study the researchers took on the little-understood process of interstitial valve-cell metabolism.

Hardly anything was known about the metabolism of heart valves, but metabolism underlies everything, Grande-Allen said. Its one of the cells main orders of business.

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High blood-sugar levels may harden heart valves