Using cardiac adult stem cells to repair heart tissue

One of the strong messages from the stem cell meeting in San Francisco over the weekend was that stem cell research needs to show some new successes soon. For many reasons, embryonic stem cell research is unlikely to provide new treatments or curescat least not in humanscwithin the next couple of years. Even though some clinical trials are planned, these are generally Phase I trials, which are intended to test the safety not the efficacy of stem cell treatments.

A new federal program focused on cell-based therapies that could be ready for clinical trials testing within two years announced Sept 29 that my favorite institution Johns Hopkins is one of three centers to receive five-year funding ($12 million) from the National Heart, Lung, and Blood Institute as a Specialized Center for Cell-Based Therapy for Heart, Lung and Blood Diseases (SCCT). Hopkins is the only center dedicated to new therapies for heart problems. The SCCT initiative will focus on two major projects.

Marbin's group will study the potential of using a patient's own cardiac stem cells to repair heart tissue soon after a heart attack, or to regenerate weakened muscle resulting from heart failure. By using a persons own adult stem cells instead of those from another donor, there would be no risk of triggering an immune response that could cause rejection. Marb¡n was recently successful in replicating large numbers of cardiac stem cells in the lab within a very short time, as little as four weeks. The stem cells, extracted from healthy parts of hearts not otherwise damaged by heart attack, grew to form clusters, called cardiospheres, which contain cells that retain the ability to regenerate themselves and to develop into more specialized heart cells that can conduct electrical currents and contract like heart muscle should.

Hare's group will evaluate adult mesenchymal stem cells (the stem cells in bone marrow that do not form blood cells) as a potential therapy to heal damaged hearts. Last year, his research in animals showed that stem cells harvested from one pig's bone marrow and injected into another pig's damaged heart restored heart function and repaired damaged heart muscle by 50 percent to 75 percent after just two months of therapy. In March 2005, Hare and other researchers began a Phase I clinical trial to test the safety of injecting adult stem cells at varying doses in patients who have recently suffered a heart attack. In total, 48 patients will participate in this study, which involves several sites across the country, including Hopkins. Results are not expected until mid-2006. Because mesenchymal stem cells are in an early stage of development, they, too, avoid potential problems with immune rejection, in which every humans immune system might attack stem cells from sources other than itself.

Marie Godfrey, PhD

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