Stem-cell repair of infarcted myocardium: ready for clinical application?

In cell culture, adult bone marrow stem cells can develop the phenotypic characteristics of myocytes and endothelial cells, and express myocyte-specific and endothelium-specific proteins. In subsequent animal laboratory studies and early clinical trials, stem cells have been delivered to infarcted myocardium by direct injection, by intravascular injection, and by bone marrow stimulation. In animals, myocyte apoptosis is reduced, capillary density increases, and regional perfusion increases accompanied by a decrease in infarct size. Early clinical trials indicate that a variety of approaches is technically feasible and safe in the short term. The trials suggest that stem-cell therapy may induce a modest preservation of cardiac function. The methodology for clinical application of stem-cell therapy currently exists in most large heart hospitals. Nonetheless, until theoretical and practical limitations are resolved, it seems prudent to confine this therapy to randomized clinical trials.