“These results provide strong evidence that human cardiac muscle cell grafts meet physiological criteria for true heart regeneration," said Dr. Michael Laflamme, University of Washington associate professor of pathology and member of the UW Center for Cardiovascular Biology and the Institute for Stem Cell & Regenerative Medicine.. "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. Injured hearts that received the human cardiac muscle cell grafts showed partial re-muscularization of the scarred left ventricle.
“We showed a couple years ago that transplanting human embryonic stem cell-derived heart muscle cells improves the pumping activity of injured hearts,” said Dr. Laflamme, “In this recent study we show that the transplantation of these cells also reduces the incidence of arrhythmias [heart rhythm disturbances].”
Scientists had been worried that transplanting heart muscle cells derived from embryonic stem cells would promote arrhythmias.
“Instead, they suppress arrhythmias, at least in the guinea pig model,” Laflamme and his team were pleased to discover.
During a myocardial infarction the flow of oxygen-rich blood to the heart muscle is interrupted by formation of a clot, causing death of the down-stream heart muscle 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.
Adapted from the University of Washington announcement.