The challenge now is to find out just how well these new cells can perform new tricks in their new homes. About 1.1 million Americans suffer heart attacks every year, and 450,000 die as a result. A heart attack occurs when a blockage in coronary arteries reduces blood supply to the heart muscle, suffocating cells. Death typically results if more than 40 percent of the left ventricle, the heart's main pumping chamber, is damaged. Nor does the damage necessarily end there.
Medications can help, but researchers increasingly are looking for biological fixes.
One of the new studies, conducted by researchers from the National Human Genome Research Institute in Bethesda, Md., and New York Medical College in Valhalla, N.Y., will appear in the April 5 issue of the journal Nature. They isolated stem cells from the bone marrow of male mice. To easily trace the cells' activity, they were reengineered with a gene that produces a fluorescent green protein. The cells were injected into the rapidly beating hearts of 30 female mice in which heart failure was induced. Over an average of nine days, the stem cells turned into heart muscle cells, filling in 68 percent of the damaged areas in the hearts of 12 mice.