Stem cells improve hearts after attacks, study shows

Using stem cells harvested from patients' own bone marrow, researchers reported Wednesday that they improved cardiac function in heart-attack patients months, years — even decades — after the patients suffered their attacks.

The infusion of stem cells boosted cardiac pumping efficiency by 7 percent in three months — a modest gain, but still a significant improvement for a chronic condition.

In one case, a patient who had suffered a heart attack 30 years earlier showed an 11 percent improvement after the treatment, according to the study published in the New England Journal of Medicine.

The German researchers also found tentative signs that patients can continue to improve with repeated stem-cell treatments.

"We have always thought that a heart attack is permanent damage, but now there is the potential that this damage can be repaired," said Dr. Christopher Cannon, a cardiologist at Brigham and Women's Hospital in Boston, who was not involved in the research.

Although the researchers are uncertain why the therapy works, the findings are a sign that the long-touted regenerative powers of stem cells may be moving from the laboratory into the realm of viable human therapies.

Some researchers cautioned that it was too soon to say that the results could be translated into routine treatment.

"There are a number of therapies that have gotten to this step, but when subjected to more rigorous trials have not worked," said Dr. Gregg Fonarow, a professor of cardiovascular medicine at the University of California, Los Angeles. "This is a therapy that may or may not pan out."

Dr. Andreas Zeiher, chair of the department of medicine at Johann Wolfgang Goethe University in Frankfurt, Germany, and senior author of the study, said the preliminary results pointed to potential new strategies for treating chronic heart disease, a condition for which there is currently no cure.

The current study focused on adult stem cells, of which there are many types, each focused on regenerating a specific group of tissues to help the body repair normal wear and tear.

Stem cells from bone marrow have been used for decades to regenerate blood and immune cells in cancer patients. Laboratory experiments suggest that these cells — or others found in bone marrow — can also make heart muscle, blood vessels, nerve cells and other tissues.

About 1.2 million heart attacks occur in the United States per year, leading to nearly 500,000 deaths, according to the American Heart Association.