April 1, 2008 (Chicago) -- Injections of patients' own muscle cells into scarred areas of the heart helped people with heart failure breathe a little better, walk a bit farther, and generally feel better.
But there was no evidence that their hearts were able to pump blood more effectively, and enlarged hearts did not shrink.
Importantly, the treatment was safe -- a huge concern due to the patients' deteriorating health, says Patrick W. Serruys, MD, of Erasmus University Medical Center in Rotterdam, Netherlands.
The results are so promising, he tells WebMD, that the researchers are recruiting heart failure patients for an FDA-sanctioned study pitting the muscle cell shots against sham injections.
"That will be the ultimate [test] of the treatment," Serruys says.
He reported the new findings here at a meeting sponsored by the Society for Cardiovascular Angiography and Interventions, being held in conjunction with the American College of Cardiology summit.
Muscle Cells Directly Injected
The researchers studied 47 heart attack survivors who had developed heart failure, a condition in which the heart is enlarged and unable to pump blood well enough to keep up the body's demand. All had implantable cardioverter defibrillators (ICDs) that detect when the heart goes into a life-threatening abnormal heart rhythm -- and then shock it to a normal rhythm.
The researchers extracted cells called myoblasts from the thigh muscles of about two-thirds of the participants and grew the cells in a lab until there were hundreds of millions of muscle cells.
Myoblasts are cells that normally lie dormant in the muscle, but after injury are mobilized to proliferate and fuse with one another to regenerate new muscle fibers.
The cells were then directly injected through a catheter into the area of the heart where muscle had died during the heart attack. Because the myoblasts came from the patient's own thigh muscles, there was no risk of rejection.
The rest of the participants were given the best available drug therapy.
Myoblast Injections Help Patients Walk Further
After six months, people who were treated with the myoblasts could walk nearly 200 feet farther in six minutes than before; those given drug treatment gained almost no distance. Given how sick these patients were before treatment, 200 feet "is a substantial gain," Serruys says.
Several patients given the muscle cell injections who had been comfortable only at rest before treatment could more easily perform everyday activities such as going to the store afterward. In contrast, nearly half of the patients taking medication got worse.
But left ventricular ejection fraction, a measure of the heart's pumping ability, dropped more in the cell-therapy group than in the drug group, although the difference was so small it could have been due to chance.
And the diameter of the heart's left ventricle -- the heart's main pumping chamber -- was larger in the cell-treated group. When the size of the left ventricle is increased, a diseased, enlarged heart pumps less efficiently.
Myoblast treatment was not associated with an excess of irregular heart rhythms, which had been the major safety concern, Serruys says.
American Heart Association spokesman Gordon Tomaselli, MD, chief of cardiology at Johns Hopkins, says this is a reassuring finding.
"Delivered in this fashion, myoblasts appear to be safe," he tells WebMD. "As far as effectiveness, the results are pretty mixed."
Tomaselli notes that direct injections of stem cells and bone marrow cells are also being tested as a way to mend broken hearts.
He says that several studies under way should help to clarify the role of the approaches in the treatment of heart failure.