Most conventional therapies for myocardial infarction -- heart attack caused by suspension of blood flow -- help ensure damage to the heart doesn't progress or recur, but don't repair damage already done. Because embryonic stem cells can generate diverse cell types in the body, including heart cells, the Mayo Clinic researchers investigated whether transplantation of such stem cells could repopulate heart muscle scarred by heart attack and produce a beneficial long-term outcome.
"The heart has a limited capacity for self-repair," says Andre Terzic, M.D., Ph.D., a specialist in cardiac biology and lead investigator of the study. "However, based on our experimental findings, embryonic stem cells present an opportunity for reparative therapy with stable benefit in myocardial infarction."
Mayo Clinic researchers induced myocardial infarction in rats, and then injected rodent embryonic stem cells into the injured heart muscle. Over time, the transplanted stem cells transformed themselves into heart cells that integrated with the surrounding muscle and reduced the scarring normally associated with heart attacks. Within three weeks, the researchers saw improved heart function, particularly within the damaged area, compared to animals that did not receive stem cell therapy. It was a clear benefit that did not diminish over the 12 weeks of follow-up. Furthermore, the response to stress was superior in the stem cell-treated hearts, and there were no deaths or evidence of abnormal heart rhythms.
Significance of Discovery
Because the advantage of embryonic stem cell delivery occurs early and does not diminish over time, this suggests a significant therapeutic potential of stem cells in the long-term management of cardiac disease. By regenerating diseased myocardium and promoting cardiac repair, embryonic stem cells provide a unique therapeutic opportunity to reduce disability or death from heart attacks.
In addition to Dr. Terzic, others involved in the research include members of his laboratory: Denice Hodgson, M.D., Atta Behfar, Leonid Zingman, M.D., Garvan Kane, M.D., Carmen Perez-Terzic, M.D., Ph.D., Alexey Alekseev, Ph.D. and Michel Pucéat, Ph.D. [Stable benefit of embryonic stem cell therapy in myocardial infarction (2004). Am J Physiol Heart Circ Physiol 287, H471-H479.]
The research was supported by the National Institutes of Health, the American Heart Association, the Marriott Foundation, Miami Heart Research Institute, Mayo-Dubai Healthcare City Research Project, Mayo Clinic, as well as by Association Francaise contre les Myopathies and Fondation de France through a collaborative effort with the French National Institute for Medical Research.