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Researchers on Medical Staff at Baylor University Medical Center Perform Research Trial Using Adult Stem Cells to Treat Heart Failure

Findings Presented at American Association for Thoracic Surgery Meeting in Toronto, Canada

(DALLAS, April 25, 2004) - Injections of adult stem cells into damaged heart tissue can significantly improve heart function in patients with severe congestive heart failure, according to results of the first prospective randomized trial of the experimental therapy presented today at the meeting of the American Association for Thoracic Surgery.

Congestive heart failure, a medical condition in which the heart is unable to pump enough blood to meet the body's metabolic needs, affects more than 5 million people in the U.S. Nearly 550,000 new cases are diagnosed every year, making it the most rapidly growing cardiovascular disorder.

Amit N Patel, M.D., M.S., principle investigator and director of clinical research, along with Harold C. Urschel, Jr., M.D., chair of cardiovascular and thoracic surgical research, education and clinical excellence at Baylor University Medical Center at Dallas, and their colleagues from Argentina and Pittsburgh say their findings offer the first convincing evidence that transplantation of adult stem cells, which may promote growth of blood vessels and heart muscle, can be a viable treatment for congestive heart failure.

"After a heart attack, the heart is unable to repair itself. The idea behind this study is that an adult's own stem cells introduced into a heart damaged from heart attack or chronic illness can differentiate into heart muscle cells and cells that promote new vessel growth, thereby improving the heart's ability to contract," said Dr. Urschel.

This is the first group of patients in a multi-center trial with severe heart failure who had ejection fractions less than 35 percent. Ejection fraction is a standard measure of heart function and is determined by the total amount of blood that the left ventricle pumps out per heart beat. A normal ejection fraction is at least 55 percent. Each of the patients was scheduled for off-pump (beating heart) cardiac bypass surgery; 10 were randomized to also receive stem cells during surgery. The other 10 patients underwent the bypass operation alone.

After undergoing anesthesia, those patients selected to receive stem cells had bone marrow removed from their hip bones. While off-pump beating heart bypass surgery was taking place, the particular stem cells that influence blood vessel and heart muscle growth were isolated from other cells in the bone marrow. After completion of the bypass, the surgeons then injected the cell preparation into 25 to 30 sites where muscle damage was apparent.

"In this procedure, both the stem cell harvest and transplant are performed during one procedure. This is very different from most other stem cell transplants where the stem cells are harvested, grown in culture, and then re-implanted into the patient at a later date after enough stem cells have been grown," said Dr. Urschel. "And because the patient's own bone marrow is used to harvest the cells, no anti-rejection medications are needed and the risks associated with transplants are greatly reduced."

Before surgery, the average ejection fraction in the patients randomized to bypass surgery alone was 30.7 percent. The patients randomized to receive stem cells in addition to bypass surgery had an average ejection fraction of 29.4 percent before treatment.

At one-, three- and six-month follow-up, the ejection fraction rates for the stem cell patients were significantly improved compared to the other patients. At one month, the stem cell patients improved to an average ejection fraction of 42.1 percent compared to an improvement to 36.4 percent on average in the control group. Three months after surgery, the stem cell patients continued to improve with an average ejection fraction of 45.5 percent compared to a rate of 36.5 percent in the other patients. At six months, the average ejection fraction rates were 46.1 and 37.2 percent, respectively.

"We don't know if this increase is due to the growth of new heart muscle cells or blood vessels resulting from the stem cell injections or whether the stem cells coax existing cells to come out of hibernation," Dr. Patel said. "What we do know is that stem cell transplantation has led to significant improvement in cardiac function in these patients undergoing off-pump bypass surgery. But, further investigation is needed to replicate these results, quantify the optimal timing of injection and to look at the cellular effects of the therapy."

The 20 patients in the study underwent treatment at centers in South America under the direction of Dr. Patel and Dr. Benetti. The researchers obtained the necessary institutional and government health agency approval to conduct the study and all patients provided informed consent. More than 40 patients have been enrolled in the multi-center trial.

A separate study is underway for patients with inoperable congestive heart failure whereby the stem cells are injected into the heart using a minimally invasive surgical technique. Two patients have undergone the procedure performed by the same team and their colleagues in Uruguay .

"This study has significant implications for how we can treat patients with severe cardiovascular disease. None of these patients have experienced severe side effects or complications as a result of the injections. This procedure may soon be available at Baylor through a research protocol," said Dr. Urschel.

In addition to Drs. Patel and Urschel, other researchers involved in the study were senior author Federico Benetti, M.D., Luis Geffner, M.D., Roberto F. Vina, M.D., and Jorge Saslavsky, M.D., of the department of cardiovascular surgery at the Benetti Foundation in Rosario, Argentina; and Robert Kormos, M.D., professor of surgery at the University of Pittsburgh School of Medicine.