Marrow cells boost ailing hearts.

Extracting cells from a heart attack patient's bone marrow and then inserting them into the person's heart via a catheter can improve pumping capacity, a new study shows.

Previous attempts to seed damaged hearts with marrow cells provided mixed results, but a research group in Germany reports clear gains in a 4-month trim in which patients and their doctors were kept in the dark as to who was getting marrow cells versus a placebo. It's the largest study to show that self-transplant can repair damaged heart tissue, says Volker Schachinger of J.W. Goethe University in Frankfurt.

He and his colleagues identified people at 17 medical centers across Europe immediately after they had survived a heart attack. All the patients were initially treated with a balloon-tipped catheter to clear the coronary artery blockage that had caused the heart attack. They also received standard drugs as needed.

The researchers extracted bone marrow samples from 204 patients who agreed to participate in the trial. Later the same day, all the patients received an infusion via catheter at the site of the coronary blockage. Half the patients received purified marrow cells, while the others got their own blood serum as a placebo.

Shortly after having their heart attacks, patients in the two groups averaged a blood-pumping rate roughly 47 percent of normal. Doctors consider 65 percent the minimum for a healthy heart. Four months after treatment, people getting marrow cells had boosted their pumping rate to 54 percent of normal levels, whereas individuals in the other group had risen to 50 percent, Schachinger reports.

Some patients getting marrow cells received them 5 days or more after a heart attack. Curiously, they fared better than did those getting the marrow more promptly, Schachinger says. Immediately after a heart attack, "there might be a hostile environment in the [heart] with inflammation and stress" that makes it difficult for the new cells to take hold, he suggests.

In another study, Schachinger and his colleagues found significant improvement in pumping capacity in people who received marrow transplants 3 months to 12 years after a heart attack.

The scientists don't know how these cells boost pumping. Nascent marrow cells may evolve into heart-muscle cells, but Schachinger considers that unlikely. Rather, the marrow cells might develop into cells that boost growth of surviving heart cells. Or they might become blood vessel cells, which are in short supply in damaged heart tissue, Schachinger says.