Stem Cells not yet Clear on Heart Repair

Heart failure patients received questionable benefit from stem cells

(RxWiki News) A patient's own bone marrow cells may be able to repair hearts weakened by heart failure by improving their pumping ability. The improvement in a recent study was considered small, but significant.

The research, though still limited in size, marked the largest study to date in using stem cells to repair heart damage caused by chronic ischemic heart disease and left ventricular dysfunction.

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Dr. Emerson Perin, director of clinical research for cardiovascular medicine at the Texas Heart Institute and the study’s lead investigator, said that the findings were the type of data needed to move ahead stem cell therapy clinical trials.

During the randomized multi-center study, conducted by the Cardiovascular Cell Therapy Research Network between 2009 and 2011, 92 patients received either stem cell therapy or a placebo. The patients were an average age of 63. They had chronic ischemic heart disease and an ejection fraction of less than 45 percent along with heart failure and/or chest pain, and were no longer candidates for revascularization.

Doctors aspirated bone marrow from the patients receiving stem cell therapy. After obtaining the mononuclear fraction of the marrow, a catheter into the heart's left ventricle was used to inject stem cells into about 15 damaged sites. Electromechanical mapping images of the heart were used to pinpoint areas that were damaged.

Researchers found that patients receiving the stem cell therapy had a 2.7 percent boost in left ventricular ejection fraction, a measure of the amount of blood departing the heart's main chamber.

After additional testing on patients' bone marrow cells to study functional characteristics, investigators also found that younger patients tended to have higher ejection fractions, or the volume of blood pumped out of the heart's right ventricle, after stem cell treatment.

Though the study reported findings that were optimistic, some doctors in attendance at the conference where the research was presented expressed skepticism about the results, mostly since the primary study findings came from numerous secondary hypotheses, such as improved ejection fraction. The study failed to meet pre-specified improvement end points in most measures of heart function.

An assessment at six months did not find a statistical difference between the therapy group and placebo group in left ventricular end-systolic volume, which was reviewed by echocardiography; maximal oxygen consumption, and reversibility on SPECT.

Dr. Robert Califf, director of the Duke Translational Medicine Institute, called the overall research findings "negative" and said he's doubtful that the results could be reproduced.

This study, funded by the National Heart, Lung, and Blood Institute, was presented Saturday at the American College of Cardiology’s Annual Scientific Session.

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Review Date: 
March 25, 2012