A study of mice has shown that mature heart cells can not only replicate, but also improve the organs function, if there are given the right environment.
The researchers noted that a sponge-like patch, soaked in a compound called periostin, and placed over the injury can help heart cells to begin dividing and making copies of themselves again.
Periostin is a component of the material that surrounds cells and is derived from the skin around bone. Though the mature heart only has tiny amounts, it is abundant during foetal heart development, and increased amounts are also made after skeletal-muscle injury, bone fracture and blood vessel injury, stimulating mature, specialized cells to begin dividing again.
Dr. Bernhard Kuhn of the Department of Cardiology at Children's Hospital Boston led a study to theorise that placing periostin near the site of a myocardial infarction could help restore this growth-friendly environment, and get heart tissue to regenerate.
The researchers first stimulated mature, rod-shaped heart muscle cells (known as cardiomyocytes) with periostin in a Petri dish. About one per cent of the cells entered the mitotic cell cycle -- namely, they began dividing and replicating.
"We found a small subpopulation of cells that could, with proper stimulation, re-enter the cell cycle. "This finding supports the idea that differentiated cardiomyocytes can proliferate," Nature Medicine quoted Kuhn, who was awarded the Young Investigator's Award for this research by the American College of Cardiology in March, as saying.
Using a small patch fashioned from a sponge-like material called Gelfoam, the researchers then moved to experiments in rats with induced heart attacks. In half the rats, a patch that had been incubated with periostin was placed over the infarct site, while the rest received Gelfoam only.
Twelve weeks later, the treated patches were still releasing biologically-active periostin. The periostin-treated rats had improved cardiac pumping ability, as indicated by increased ejection fraction and improved ventricular remodeling on echocardiograms, and decreased left-ventricular wall stress on catheterization.
The periostin-treated rats also had less scarring of heart tissue, a reduction in infarct size, and a denser network of blood vessels feeding the area. In contrast, the rats receiving Gelfoam alone did not show any significant improvement.
The researchers believe that a sustained-delivery periostin patch may one day be helpful in treating adults with heart attack, and in encouraging cardiomyocyte proliferation in children with congenital heart disease.
"Many patients with severe congenital heart disease eventually hit a place where the heart isn't pumping adequately," Kuhn says.