For the first time, researchers have been able to show that injections of stem cells into enlarged hearts reduced heart size and scar tissue, and improved function to injured areas of the heart. This small trial was published in Circulation Research: Journal of the American Heart Association. While this research is in the early stages, these findings hold tremendous promise for the more than five million Americans who have enlarged hearts due to damage sustained from heart attacks. Heart patients suffer from premature death and have major disabilities. Heart attack patients also experience frequent hospitalizations. Treatment options are also limited to lifelong medications and major medical interventions like heart transplantation.
By using catheters, these researchers injected stem cells derived from the patient’s own bone marrow into the hearts of eight men (average age 57), wll of whom suffered from chronically enlarged, low-functioning hearts. Joshua M. Hare, M.D., the study’s senior author and professor of medicine and director of the Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, University of Miami in Miami, Fla, said, “The injections first improved function in the damaged area of the heart and then led to a reduction in the size of the heart. This was associated with a reduction in scar size. The effects lasted for a year after the injections, which was the full duration of the study.”
Specifically, these data showed that 1) heart size decreased an average of 15 percent to 20 percent, which is about three times what is possible with current medical therapies; 2) scar tissue decreased by an average of 18.3 percent and; 3) there was dramatic improvement in the function, or contraction, of specific heart areas that were damaged.
Hare continued, “This therapy improved even old cardiac injuries. Some of the patients had damage to their hearts from heart attacks as long as 11 years before treatment.”
The researchers had used two different types of bone marrow stem cells in their study — “mononuclear” (bulk bone marrow stem cells) or mesenchymal stem cells. The study lacked the power to determine if one type of cell works better than the other, but all patients in the study benefited from the therapy and tolerated the injections with no serious adverse events.
Hare’s study assessed the effect of stem cell injections differently from other studies of post-heart attack stem cell treatment. His team measured contractility, scar size and structural changes of the heart. “Studies of bone marrow cell therapy for ischemic heart disease in animals have shown improved ejection fraction (the amount of blood the heart can pump). However, this measurement has not reliably translated to early phase studies in humans,” Hare said. “Ejection fraction may not be the best way to measure the success of stem cell therapy in the human heart.”
Hare also said their findings suggest that patients’ quality of life could improve as the result of this therapy because the heart is a more normal size and functions better. Hare cautioned, “we have yet to prove this clinical benefit – this is an experimental therapy in phase one studies. These findings support further clinical trials and give us hope that we can help people with enlarged hearts.”