A key reason heart attacks are so dangerous is that they kill heart muscle cells. In humans, these cells have a limited ability to regenerate, so scar tissue builds up, making it more difficult for the heart to circulate blood.
But heart muscles in the zebrafish, which regenerate after being damaged, have given Duke scientists a few ideas that may lead to new directions in clinical research and better therapy after heart attacks. Research conducted by Kenneth Poss, professor of cell biology, shows that a certain kind of heart muscle cell, called a cardiomyocyte, is likely responsible for the regenerative effects. Identifying these cells provides a target for future studies into cardiac muscle regeneration, which may eventually be used as therapy for heart disease in humans.
Researchers at Duke also found that the cardiomyocytes were beginning to synchronize with the rhythm of the muscle that was spared by injury—within two weeks the regenerated tissue was beating in concert with the normal tissue. This is the first time that evidence has suggested this electrical coupling.
A third finding was that the zebrafish heart muscle works around scar tissue, which has interesting implications for treating the human heart. Normal zebrafish cardiac cells don't scar, but the researchers manipulated them so that they would. When the scar tissue formed, as it does in the human heart, the cardiomyocytes still produced new cells surrounding the damaged area.