Diabetes Diminishes Capillaries Surrounding the Heart

Numerous studies have established a significant link between diabetes and an increased risk of heart disease and cardiovascular events, such as a heart attack; however, the exact causes remain unknown.

In a new study published by the Journal of the American College of Cardiology, the authors discovered that diabetes causes the loss of small blood vessels around the heart, which effects its function. Investigators suggest that gene therapy designed to promote the growth of novel blood vessels may be an effective treatment for patients with diabetes.

While veins and arteries are crucial for blood circulation to the heart and the body, the loss of small vessels can cause significant problems. If the veins and arteries become overworked, they could eventually stop, resulting in a heart attack.

In the study, the authors examined blood vessels from patients with and without diabetes who were undergoing heart transplants. They discovered that patients with diabetes had a substantially reduced amount of small blood vessels around the heart.

The findings also showed that high blood glucose levels resulted in a loss of pericytes, according to the study.

"These cells normally form a layer wrapped around the small blood vessels," said researcher Dr Rabea Hinkel. "We believe that this layer has a stabilizing function. When it is damaged, the entire blood vessel becomes unstable and ultimately breaks up."

Analyses in animal models confirmed that capillary density decreased around the heart when diabetes was uncontrolled, which highlights the importance of treatment to prevent complications, according to the study.

“Diabetes often remains undetected in patients for years or even decades,” Dr Hinkel said. “Over that long period, massive damage can occur.”

Unfortunately, capillary loss is not reversible with current treatments. However, the study authors believe that gene therapy may be able to restore capillaries to prevent heart attacks among patients with diabetes.

The authors applied gene therapy that was designed to cause heart cells to increase the production of thymosin beta 4, which is a protein that stimulates the growth of pericytes, in an effort to increase capillaries around the heart. They found that this treatment led to the creation of lasting and functional capillary networks, according to the study.

Additional studies are needed to determine if this type of gene therapy can lead to significant results in humans.

"It will be a while before this kind of therapy can be used in humans," concluded researcher Christian Kupatt, PhD. "But we were able to show for the first time in a transgenic large animal model, which closely models human type I diabetes mellitus, how diabetes damages the heart. That opens up new perspectives for treating patients. It also further reinforces our awareness of how important it is to diagnose diabetes early."