While some people are born with heart defects that lead to a transplant, like Moore, others require a new heart because of the damage done by small and large heart attacks over a lifetime. In the not-too-distant future, predicts Eduardo Marbán, director of the Cedars-Sinai Heart Institute, an infusion of stem cells may provide a better solution for these patients. "We hope to create a viable alternative to transplants for patients with advanced heart disease," says Marbán, who, with colleagues, developed the new procedure. "We have a glimmer of hope with our early work."
That work was described in a head-turning Lancet paper in February. Stem cells in the heart naturally replace about 1 to 2 percent of heart cells a year, just to keep up with the wear and tear of daily life. But in a heart attack, says Marbán, a person can lose 40 percent of heart muscle overnight. By taking biopsies of heart muscle from patients after their heart attacks, growing stem cells outside the body, and injecting them back in, his group theorized, they could speed up the natural regenerative process. Indeed, Marbán's team found that patients given a dose of cardiac stem cells derived from their own hearts saw their scar tissue shrink by half over the next year whereas people who didn't get the treatment saw no shrinkage. And the patients treated with their own heart cells actually grew some new heart muscle.
Other researchers have tried using stem cells derived from bone marrow to treat heart damage, without appreciable results. The new technique, says Marbán, appears to be the first that "can reverse an injury thought to be permanent."
Although researchers haven't confirmed it, a person who has been partially healed by stem cells might logically be at lower risk of developing heart failure, and of eventually needing a transplant. Marbán's next steps are to look at the possibility of preparing cardiac stem cells from donor hearts that couldn't be used for transplants either because they were too small or the wrong blood type. Eventually, he hopes, the best medicine for a failing heart will be a simple quick shot.
Meanwhile, Michelle Johnson waits for her new one.