MONDAY, March 22, 2004 (HealthDayNews) -- In a study that contradicts earlier findings, Stanford University researchers conclude that blood-forming stem cells can't repair damaged heart muscle after a heart attack.
In recent years, several studies have reported that blood-forming stem cells found in bone marrow could lodge in the heart and repair heart muscle damaged by heart attack.
But this new Stanford University School of Medicine study found that, in mice, these blood-forming stem cells do lodge in damaged hearts but don't transform into heart muscle tissue.
The study appears in the March 21 online issue of Nature. Another study in the same issue used slightly different methods but reached the same conclusion.
In related news, two trials using stem cells to repair heart damage were halted due to dangerous results. South Korean scientists stopped a trial in which heart attack patients were given infusions of their own stems cells. Many of the patients' heart arteries opened by the stem cell treatment unexpectedly began to close again.
A similar trial in dogs was halted by University of California at Davis scientists. They detected a high incidence of tiny pockets of cell death called microinfarcts in the dogs.
Both those studies appeared in the March 6 issue of The Lancet.
The U.S. National Institutes of Health has more about stem cells.