Stem cell research could have long-term implications for cardiology

November 14, 2006

After years of minimal results, stem cell research is forging ahead. "This is a new appetizer for what may be an excellent meal in years to come," said former AHA president Valentin Fuster, MD, PhD, at a press briefing Tuesday morning. "Reports the past couple of years have been equivocal at best."

After years of minimal results, stem cell research is forging ahead.

"This is a new appetizer for what may be an excellent meal in years to come," said former AHA president Valentin Fuster, MD, PhD, at a press briefing Tuesday morning. "Reports the past couple of years have been equivocal at best."

Three papers have reported success using stem cells from amniotic fluid, adipose tissue, and bone marrow. A fourth report shows early evidence that marrow stromal cells may be universal donor cells that do not elicit an immune response.

"Stromal cells may have unique healing properties," said Ray Chiu, MD, PhD, professor of surgery and chair emeritus of cardiothoracic surgery at McGill University Health Center in Montreal, Quebec, Canada. "It looks like they may be tolerated by everybody."

Dr. Chiu's group injected commercially available human stromal cells into rat hearts following induced myocardial infarction. Two months later, the human cells were still present, healthy, and reproducing.

"What this means is that you can have cells from young, healthy donors in the refrigerator, ready for transplanting off the shelf," Dr. Chiu said.

Until that happens, clinicians will have to make do with other sources. Swiss researchers reported success using amniotic stem cells seeded onto a biodegradable polymer to grow heart valves. The goal is to produce autologous valves for implantation in infants.

About 1% of infants are born with heart defects, said Simon Hoerstrup, MD, PhD, professor of biomedical engineering and director of cardiovascular research and the division of regenerative medicine at University Hospital, Zurich, Switzerland. A third of them need immediate surgical intervention.

"The advantage is that these valves come from the baby's own cells," Dr. Hoerstrup said. "We can prefabricate a heart valve that can be ready to implant at the time of birth."

There is good news for older patients, too. Paul DiMuzio, MD, associate professor of surgery, Thomas Jefferson University, Philadelphia, Pa., found that stem cells harvested from the adipose tissue of elderly patients are as healthy and as numerous as those from younger donors.

Dr. DiMuzio harvested about 15 grams of adipose tissue from elderly patients, harvested the stem cells and cultured them for a week.

"We were pleasantly surprised," he said. "As you go from decade to decade, we did not see any decline in the harvest of stem cells. They all look the same, they were healthy, and they grew well."

The news is even better for heart attack patients. A German team found that infusing bone marrow stem cells into the cardiac artery following myocardial infarction increased both injection fraction and ventricular volume. The worse the infarct was, the greater the beneficial effect.

"The sicker the patient, the greater the impact on ejection fraction," said Thorsten Dill, MD, Department of Cardiology and Cardiac Imaging, Kerckhoff-Heart Center, Bad Nauheim, Germany. "The lower the ejection fraction following infarct, the greater the treatment benefit. Bone marrow stem cells hold great promise to limit infarct damage."