Heart failure develops when the heart stops pumping effectively due to the destruction of muscle cells, known as cardiomyocytes. Damage inflicted during a heart attack causes massive loss of cardiomyocytes, resulting in ventricular dysfunction. Although heart transplantation has proven very successful, only a small number of organs are actually available for transplant each year. That’s why heart disease has been a focus of stem cell research for a number of years, with promising results shown in mice. According to the results of an animal study conducted at Beth Israel Deaconess Medical Center, transplantation of embryonic stem cells can help repair injured heart muscle and improve cardiac function following heart attacks and the development of congestive heart failure. “Congestive heart failure is the last major area of cardiac medicine that remains without a readily available effective treatment,” explains cardiologist James Morgan, Herman Dana Distinguished Professor of Medicine at Harvard Medical School and co-author of the study, which appeared in the January 2001 issue of the Journal of Applied Physiology. The study was funded with support from the National Institutes of Health and the American Heart Association.