March 18, 2011 — Stem cell researchers have shown for the first time that stem cells injected into enlarged hearts reduced heart size, reduced scar tissue, and improved function to injured heart areas. The findings, from a small trial conducted at the Interdisciplinary Stem Cell Institute at the University of Miami Miller School of Medicine, are published in the March 17 issue of Circulation Research: Journal of the American Heart Association.
“While this research is in the early stages,” says Joshua M. Hare, the study’s senior author and director of the Interdisciplinary Stem Cell Institute, “the findings are promising for the more than five million Americans who have enlarged hearts due to damage sustained from heart attacks.” These patients can suffer premature death, have major disability, and experience frequent hospitalizations. Options for treatment are limited to lifelong medications and major medical interventions, such as heart transplantation.
In this study, physicians used a corkscrew-shaped catheter to inject stem cells retrieved from the patient’s own bone marrow. The patients were eight men, average age of 57, who had chronically enlarged, low-functioning hearts.
“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,” Hare said. The effects lasted for a full year after the injections, the full duration of the study.
Specifically, the Miller School researchers found that the heart size decreased an average of 15 to 20 percent, or about three times what is possible with current medical therapies. Scar tissue went down by an average of 18.3 percent, and there was dramatic improvement in the function of specific heart areas that were damaged.
“This therapy improved even old cardiac injuries,” Hare said. “Some of the patients had damage to their hearts from heart attacks as long as 11 years before treatment.”
Alan Heldman, professor of medicine who leads the team injecting stem cells into the heart, describes the findings as “a real breakthrough in the field. These results are key evidence that this cell population holds great potential for producing positive effects that we haven’t been able to achieve with current therapies.”
Hare and the team used two different types of bone marrow stem cells in the study—mononuclear or mesenchymal stem cells. The study did not examine whether one type of cell works better than the other. All patients in the study benefited from the therapy and tolerated the injections with no serious adverse events.
The study assessed the efficacy of stem cell injections by measuring contractility, scar size, and structural changes of the heart. Hare said their findings suggest that patients’ quality of life could improve as a result of this therapy because the heart is a more normal size and is better functioning. “But, 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.”
The double-blind, placebo-controlled portion of this study is continuing and expected to conclude by the end of summer 2011.
