The findings are presented in the May 13, 2003 issue of Circulation: Journal of the American Heart Association, published early online.
Congestive heart failure is the inability of the damaged heart muscle to pump enough blood to serve the body's needs. It is a fairly common and debilitating condition, responsible for over 50,000 deaths a year.
Stem cells are at an early stage of maturation, and therefore have the potential to become many different types of cells - including those in the heart muscle. Stem cells have been at the center of controversy because they are often taken from embryos. But that is not the only source of stem cells.
The stem cells used in this study were taken from the patients' own bone marrow about four hours before the procedure. Through earlier tests, researchers found that these specific cells have a high probability of becoming blood-vessel and heart cells.
This is believed to be the first study involving bone marrow stem cells injected into human hearts of patients with severe heart failure, reports researcher James T. Willerson, MD, medical director of the Texas Heart Institute at St. Luke's Episcopal Hospital in Houston.
His study involved 21 Brazilian patients, all close to death from congestive heart failure. "These patients were desperately ill," Willerson says in a news release. "They had a relatively high risk of dying, and had no other forms of therapy available because their heart failure was so severe."
Fourteen patients received an average of 15 injections containing about two million stem cells each. Seven other patients served as a comparison group, and did not receive any stem cell injections. However, both groups of patients received the same medical care and monitoring.
After two months, the treated patients had significantly less congestive heart failure and angina (heart pain); their hearts were better able to pump blood than the untreated patients. The treated group performed better on treadmill tests.
Four months later, the treated patients' hearts had a sustained improvement in pumping power and ability to supply blood to the body.
Researchers don't quite know why the patients' conditions improved. "Either these stem cells became new blood vessel and new heart muscle cells, or their presence triggered the development of one or both," says Willerson in a news release.
Further study is needed, involving larger numbers of patients, to determine the benefits and risks of the congestive heart failure treatment, he says.