The study excluded people with heart failure, which occurs when the heart muscle has become too weak to pump blood properly. But Atsma said that a trial of bone marrow cell therapy for people who have blocked arteries as well as heart failure is planned.
The bone marrow cell injections help restore blood flow by promoting the creation of new blood vessels, Atsma said, but it's not clear how this happens. "It could be that the cells that are injected become part of the vasculature, the blood vessels," he said. "Even better, the injected cells may secrete proteins that stimulate angiogenesis, formation of blood vessels. Or it might be a combination of those two things."
Whatever the reason for the benefit of bone marrow cell therapy, "we are fairly enthusiastic, considering that these patients had no alternative," Atsma said. "They had all the surgery and angioplasty they could have."
Dr. Amit Patel, director of cardiovascular regenerative medicine at the University of Utah, described the finding as "definitely a step forward in the treatment of chronic angina." But he had some cautionary comments.
It was a small study, with just 50 participants, he said, adding that "to make it a more reproducible therapy, you would have to do at least a couple of hundred patients."
Also, the follow-up period was relatively short, at three months, he noted. "Something positive happened, but you would have to follow these patients further to see how long it would last," Patel said. Future studies to determine whether there would be an overall improvement in heart function would also be welcome, he said.
Doris Taylor, director of the University of Minnesota Center for Cardiovascular Repair, also had qualified praise for the results.
"The good news is that it is more mechanistic in that it gives some insights into perfusion," she said. "It reinforces the evidence that bone marrow cells are safe and effective.
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