Stem Cell Therapy to be Tested on Human Hearts

A study conducted by scientists at Johns Hopkins University in Baltimore, Maryland, showed that heart attacks (myocardial infarction) can be treated with stem cell therapy. Research performed on pigs was a success, and a clinical trial to test the safety of the method for humans is about to get started.

The findings were first presented at the 2004 Scientific Sessions of the American Heart Association, and are to be published in today's issue of the Proceedings of the National Academy of Sciences.

14 animals that had had heart attacks were studied, 7 of which were given the stem-cell therapy. Stem cells harvested from another pig's bone marrow were directly injected into the heart muscle through a catheter, and, in just two months' time, heart muscle contraction was restored to previously existing levels and damaged heart muscle repaired by 50 percent to 75 percent. The 7 other pigs, injected with placebo, had no recovery; moreover, they developed congestive heart failure within the two months following the heart attack.

For the Phase I clinical trial on humans that is about to begin, two patients have already been enrolled at Johns Hopkins Hospital, and a total of 48 is expected to participate, at several sites across the country. The Phase I study is designed only to test the safety of injecting adult stem cells at varying doses in heart attack patients. Cardiologist Joshua Hare, M.D., professor of medicine at The Johns Hopkins University School of Medicine and lead author of the study, explains that in the initial trial, the cells will be infused into the blood stream, and after 6 months, patients will undergo an MRI scan to check their heart function. They will be watched for two years and results are expected around mid-2006. In the Phase II of the trials, a variety of methods will be used to deliver the cells, Dr. Hare explains.

Stem cells are primary cells that can grow into any other type of cell in the body. Scientists are using stem cells in an early stage of development – adult mesenchymal stem cells - to avoid the problem of immune system rejection. Embryonic stem cells have more potential, but using bone marrow adult stem cells avoids the controversy over taking cells from a human embryo.

"Ultimately, the goal is to develop a widely applicable treatment to repair and reverse the damage done to heart muscle that has been infarcted, or destroyed, after losing its blood supply", says Professor Hare.

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