More Heart Advances Made with Adult Stem Cell Research

By Amanda Gardner, The Washington Post, November 7, 2007

Stem cells are already being used to restore the functioning of damaged hearts, and now scientists are working towards gaining an even better understanding of how this works.

In Orlando, Florida, different aspects of this promise were presented on Wednesday in the form of several studies.  The event was the American Heart Association annual meeting.

One study revealed, as a preliminary finding, that the heart's ability to pump effectively was improved when a patient's own stem cells were injected into the heart as a treatment following a heart attack.

"We're still learning. The area of stem cells still needs lots of understanding," said Dr. Robert Bonow, immediate past president of the heart association and chief of cardiology at Northwestern Memorial Hospital in Chicago. "What are the right kinds of cells? How do we train them into cells that are viable and make people better? What are the right kinds of patients? We really don't know that. We're waiting for more data."

In the first study, patients were randomly assigned to receive either injections of their own bone marrow cells or a placebo.  A total of 80 patients who had recently experienced the more serious type of heart attack called an ST elevation heart attack (STEMI), and received treatment (angioplasty and clot-busting drugs), were treated.

An improvement from 59 percent to 67 percent was observed in the global ejection fraction (a measure of the heart's pumping function) of patients who had been treated with bone marrow stem cell therapy six months following treatment.  As for the placebo group of patients, the ejection fraction remained the same.

"In conclusion, intracoronary injection of autologous [from the patient] bone marrow cells improves left ventricular systolic function in STEMI patients who are treated initially with thrombolytic therapy followed by [angioplasty] two to six days after a heart attack," said Dr. Heikki Huikuri, lead investigator of the trial and professor of medicine and director of the cardiology sector at the University of Oulu Hospital in Finland. "This appears to be a safe therapy."

Bonow added: "The findings are interesting but preliminary. The ejection fraction showed a meaningful increase, but they were normal to begin with. We need more time and more information."

Boston Scientific Incorporated and the Finnish Academy of Science funded the study.

Two other studies investigated patients with chronic scar tissue from a prior heart attack; the results were less than convincing.  These studies, which looked at a different population than the Finnish study, were presented in late-breaking sessions at the AHA.

Researchers assess safety as a primary goal, but also observed effectiveness in one trial involving 23 heart-failure patients.  The patients own skeletal muscle stem cells were were injected directly into the heart.

"These cells are not designed to be heart tissue, but they do contract and have some electrical activity," Bonow explained.

The treatment yielded a better quality of life and improved heart function at one year, and proved to be safe.  But, improvements could be due to a placebo effect since the study was not "blinded".  Bonow said that minimal decrease in heart size was observed.

"This doesn't lead anywhere right now," Bonow said.

A biotech company developing cell-based therapies named Mytogen Incorporated funded the study.

Heart muscle function was found to be unaffected by injecting patients' own stem cells into heart scar tissue in the final study.

"It was safe but didn't improve systolic function, didn't reduce infarct size and didn't influence global left ventricular function," said study lead author Dr. Manuel Galinanes, professor of cardiac surgery at the University of Leicester in England.