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Bone Marrow Stem Cell Trial Approved for Heart Patients

By Nancy Touchette

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Heart Disease
Stem Cells

Emerson Perin maps the left ventricle and injects stem cells directly into the heart muscle.
The U.S. Food and Drug Administration has approved the first clinical trial in the United States to test a bone marrow stem cell therapy for severe heart failure. The trial, due to begin within the next week or so, will be led by Emerson C. Perin and his colleagues at the Texas Heart Institute in Houston, Texas.

Perin, in collaboration with Hans F.R. Dohmann at Hospital Procardiaco in Rio de Janeiro, Brazil, has already tested the treatment on 14 patients in Brazil. That study, published last year in Circulation, showed that the procedure is safe and significantly improves heart function.

“We saw significant improvements in exercise capacity,” says Perin. “This is measured in terms of peak oxygen capacity, which went from 17 percent to 24 percent in treated patients.”

Participants in the Brazilian study knew whether they were part of the treatment group that received bone marrow cells, or part of a second group that did not receive therapy. Such knowledge could affect the outcome of a study. In the new study, the 30 participants will be randomly assigned to a treatment group or a placebo group without knowing which group they’re joining.

Twenty patients will receive injections of their own bone marrow cells through a special device that maps blood flow throughout the heart and delivers the cells through a catheter. The cells will be injected into regions of the heart that are still living but receive less blood than healthy tissue.

The remaining ten patients will receive a placebo treatment. They will have their hearts examined using the same device, but will not receive bone marrow injections.

Both groups will be monitored on a weekly basis. After six months, if patients receiving the stem cell treatment show improvement in heart function, the treatment will also be offered to those in the placebo group.

Previous studies in mice examining the fate of bone marrow stem cells injected into heart muscle have been controversial. An early study in mice suggested that bone marrow stem cells could turn into heart cells and restore function to a damaged heart. But other studies suggest that the stem cells can fuse with heart cells, and still other experiments show that the bone marrow stem cells just become blood cells.

Researchers do not know whether heart function improves because bone marrow stem cells can turn into heart cells, whether the cells stimulate cardiac stem cells that reside in the heart, or whether the cells support the growth of blood vessels that improve blood flow to damaged tissue.

Because of these uncertainties, many researchers have called for a halt to the testing of stem cell therapies for heart disease in humans.

“We need to conduct any clinical trials with a cautious eye,” says Charles Murry of the University of Washington in Seattle, whose research suggests that bone marrow stem cells do not become heart tissue. “These trials should not have been started based on the evidence that was there. But they may end up being right for the wrong reasons.”

Perin suggests moving forward with the clinical studies because the Brazilian trial has shown that the procedure is safe.

“We have a lot of patients that are marching on towards end-stage heart failure,” says Perin. “Are we going to wait around, sitting on our hands while we try to figure out what is happening in mice? Or do we move forward and try to see if this treatment can help?”

Perin, E.C. et al. Transendocardial, autologous bone marrow cell transplantation for severe, chronic ischemic heart failure. Circulation 107, 2294-2302 (May 13, 2003).

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