Researchers have made a major advance in their bid to regenerate damaged heart by grafting human cardiac muscle cells into guinea pig hearts.
The grafts also reduced the possibility of irregular heartbeats (arrhythmias) in a guinea pig model of myocardial infarction, a heart attack disrupting the flow of oxygen-rich blood to the heart muscle because of a clot formation, causing the down-stream heart muscle to wither and its eventual replacement by scar tissue.
This can cause mechanical problems with filling and emptying the heart, and it can also interfere with the electrical signals that pace the heartbeat, the journal Nature reports.
The guinea pig, also called the cavy, is a species of rodent family. Despite their common name, these animals are not in the pig family, nor are they from Guinea.
Senior study co-author Michael Laflamme, from the University of Washington, said: "These results provide strong evidence that human cardiac muscle cell grafts meet physiological criteria for true heart regeneration. This supports the continued development of human embryonic stem cell-based heart therapies for both mechanical and electrical repair of the heart."
In this study, the guinea pigs' hearts had an injury to the left ventricle, the thick walled lower chamber in the heart that pumps oxygenated blood to the body. The injury left a scar and thinned the ventricle, which showed both reduced pump function and greater susceptibility to arrhythmias.
Consistent with previous studies, tests showed that the injured hearts with the human cardiac cell grafts had improved mechanical function. More surprisingly, these hearts showed fewer arrhythmias than did injured hearts without such grafts, according to a Washington statement.
"We showed a couple years ago that transplanting human embryonic stem cell-derived heart muscle cells improves the pumping activity of injured hearts," said Laflamme, associate professor of pathology at Washington.