A promising therapy for heart attacks uses stem cells to repair the damaged areas of the heart. However, getting the transplanted cells to stay at the site is a challenge. Now scientists have created a new type of off-the-shelf cardiac patch that overcomes these limitations.
The leading cause of death in the United States is coronary heart disease, which kills about 360,000 per year. Heart attacks result from the loss of blood flow to part of the heart muscle. This can be caused by fat, cholesterol and other substances forming plaque in the coronary arteries that supply oxygenated blood to the heart.
When the plaque breaks, a clot forms around it, which can prevent blood flow to a part of the heart and kill cells. The degree of damage depends on the area of the heart supplied by the blocked artery.
Treatments for a heart attack include limiting the original damage and blocking the secondary damage, which reduces long-term consequences and saves lives. As the heart heals, the damaged area forms scar tissue, which cannot pump blood like normal heart tissue, and it can affect the performance of the rest of the heart.
Cell therapy for heart attacks involves using cardiac stromal cells to encourage the heart to heal with muscle cells rather than scar tissue. Cardiac stromal cells interact with muscle cells and release chemical signals to encourage muscle cell growth.
This approach has only moderate benefits, because cardiac stromal cells are fragile and must be carefully stored and transported. Making matters worse, some stem cells can grow out of control and become tumors. Using a patient’s own cells has some advantages, but it’s expensive and time consuming. There’s also the problem of preventing the beating heart from washing the cells away.
Several types of scaffolds have been developed to keep the cardiac stromal cells at the proper location. However, these scaffolds don’t overcome the cost and difficulties of isolating and expanding the stem cells.
Now a group of scientists has created a new type of artificial cardiac patch. It consists of a scaffolding matrix made from pig cardiac tissue, from which all cells have been removed. They then created artificial cardiac stromal cells by putting the important healing components from cardiac stromal cells into biodegradable microparticles within that matrix. The synthetic cardiac stromal cells mimic the therapeutic features of live stem cells while overcoming their storage and survival problems, and the matrix preserves the structures and activity found in cardiac tissue.
The artificial cardiac patch was shown to hold the synthetic cardiac stromal cells in place on the heart. In heart attack experiments in both rodents and pigs, the patch resulted in a 50 percent improvement in heart function and a 30 percent reduction in scarring when compared to no treatment.