Heart-muscle research offers hope

Transplanted stem cells show promising signs of treating heart disease

Health & Fitness

January 26, 2003|By Thomas H. Maugh II | By Thomas H. Maugh II,Special to the Sun

New drugs and medical procedures are sharply increasing the number of people who survive heart attacks and congestive heart failure, but there is an unfortunate side effect. Survivors' mobility and lifestyles are often severely restricted because their extensively damaged heart tissue can no longer pump adequate quantities of blood throughout the body.

A growing number of researchers are attempting to circumvent such problems by regenerating heart muscle. Reports at a recent American Heart Association meeting provide tantalizing glimpses into where these efforts might be heading.

All of the trials are still "very, very early," cautioned Dr. Timothy Gardner of the University of Pennsylvania, "but what is exciting is that they have opened a treatment pathway that was not tried before."

About 7.5 million Americans will suffer heart attacks this year, according to the American Heart Association. Two-thirds will survive -- a much higher rate than in the past -- but many will have severely debilitated hearts that make them candidates for regenerative procedures.

Heart tissue has a limited ability to regenerate on its own, so the loss of extensive amounts of tissue in a heart attack is catastrophic. Some cardiologists have attempted to replace it by wrapping muscle tissue from the back around the heart and training it to contract along with the heart tissue, with only limited successes.

Now cardiologists are attempting to make use of new developments in stem cell technology to augment heart tissue. Researchers remove bone marrow or stem cells from an arm or thigh in a patient's body, grow them in a laboratory dish to increase their numbers from a few million to a billion or more, then inject them into a heart.

The hope is that the injected cells will become heart cells and integrate into heart tissues. Using the patient's own cells avoids the need for drugs to suppress the immune system, as well as the risk of rejection.

A study by Dr. Francis Pagani of the University of Michigan indicates that is indeed a possibility. Pagani and his colleagues injected cells into the hearts of five patients awaiting heart transplants. Because three of them have since received their transplants, Pagani was able to study their old hearts.

He found that the injected cells not only survived in their new environment, but also began to form muscle fibers. "These results give us the first indication that muscle cell transplants, even from an entirely different kind of muscle, could one day be used to help repair damaged, failing hearts," Pagani said.

Experts estimate about 50 people worldwide have received cell transplants in their hearts since the procedure was first attempted two years ago by Dr. Philippe Menasche of the Georges Pompidou European Hospital in Paris. Most transplants in the United States have been performed by a team headed by Dr. Nabil Dib of the Arizona Heart Institute in Phoenix. The team has injected cells extracted from thigh muscle into 11 patients during coronary artery bypass surgery and into five during implantation of a left ventricular assist device.

"We found that the transplanted [cells] survived and thrived in patients," Dib said. "Areas damaged by heart attack and cardiovascular disease showed evidence of repair and viability."

One beneficiary of the new procedure is Barry Bucchione, a 53-year-old auto mechanic who was treated at the Cleveland Clinic Heart Center in Ohio. Forty years of smoking caught up with him in 2001, when he was diagnosed with congestive heart failure. Weakened by disease, he could barely walk and had to stop working.

He received the cell injection in June of that year during bypass surgery and three months later was well enough to return to his job repairing taxicabs. Doctors do not attribute his recovery to the transplant, because he also received bypass surgery, but it is clear that the cells did him no harm. "I have no shortness of breath," he told meeting attendees. "I can run up the hill, and before, I had a problem walking half a block."

Menasche cautioned that there is a potential for problems with the procedure. He said four of the 10 patients he has treated developed ventricular tachycardia, a potentially fatal rapid heartbeat.

All were successfully treated for the problem, he said, but a separate European study by other researchers was halted earlier this year when similar problems developed and one patient in Italy died.

Thomas H. Maugh II is a reporter for the Los Angeles Times, a Tribune Publishing newspaper.

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