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Friday, March 16, 2001

With the debate over federal funding for embryonic stem cell research, opponents are pointing to the study, published in the March 8 issue of the New England Journal of Medicine, as bolstering their argument. Other researchers feel new uncertainty about the application to human disease subjects of stem cell science in animal models.

"Anything that is new, scientists obviously want to investigate," said Dr. David Prentice, a professor of life sciences and molecular studies at the University of Indiana School of Medicine and a founding member of Do No Harm: Coalition of Americans for Research Ethics.

"But this is one area of research where there is plenty of evidence that it might have unexpected and unfortunate results," he told United Press International in a telephone interview. "We've all heard that fetal stem cells might be the Fountain of Youth. I say that the water is poisoned."

Nevertheless, the study's lead researcher called the findings a very strong lead in ultimately developing treatments for the neurological disease.

"The motor problems we saw in our younger patients demonstrate the power of the transplants, and we now know that we probably have to reduce the amount of material transplanted," Dr. Curt Freed of the University of Colorado School of Medicine, Denver, told UPI.

In the first double-blind study to determine whether fetal cell transplants can be effective in restoring dopamine function in Parkinson's patients, the researchers found that the benefits were meager and the adverse effects very serious.

They reported that transplanting human fetal dopamine neurons directly into the brains of Parkinson's patients had little effect on performance on patients over age 60 after one year, when compared to a group of patients who underwent a sham procedure. In younger patients the procedure was associated with a greater incidence of movement disorder.

Calling the findings worrisome, Freed the results at this time "do not support transplants of this type."

However, he emphasized to UPI that the study's findings provide a clear road map for future studies.

Freed and his colleagues at Columbia College of Physicians and Surgeons in New York transplanted dopamine neurons directly into the brain through holes drilled through the heads of volunteers. Scientists understand that severe dopamine deficits are at least partly responsible for the progressive disease, in which patients gradually lose control over their body movements.

Many medical researchers believe that pluripotent stem cells – immature fetal cells that can be coaxed to grow into a number of body organs, nerves, tissue and blood vessels – hold far more promise that the adult versions. In recent years, researchers have made startling advances using such stem cells in treating a range of human disorders and in many animal models of human diseases.

A number of reports in the past three years have given neurological researchers and patients cause for optimism. Stem cell studies in animals have shown them to be capable of regenerating damaged nerves and bolstering diseased nervous systems. They have grown neurons in damaged spines and watched paralyzed animals move again. Investigators have observed that implanted neural stem cells, which are able to grow into any of the cell types in the brain, migrate to damaged areas and start a repair process that just a decade ago was the stuff of science fiction. Experiments in mice suggest that transplantation of bone-marrow stem cells might provide a treatment for Duchenne muscular dystrophy and other diseases involving cells that are widely distributed throughout the body.

But Do No Harm's Prentice told UPI that the trial's outcome came as no surprise to many researchers who advocate the use of adult stem cells and cord cells rather than those acquired from embryos.

"We have had some indications before that this research might not turn out, but nothing quite as negative as this," said Prentice, who is conducting research using adult stem cells. "In 1996 we had a report where a patient had been given transplanted fetal brain cells that were accidentally mixed with some other cells that went crazy when they reached the brain."

According to the researcher it is a plus-and-minus situation. "I'm well aware of the studies that show the potential benefits of stem cells, but it may be time to rethink this entire field of study," he said.

"I'm not even sure why we're having this debate. If we've learned any lessons from this study it is that there are signs of serious problems down the road."

Prentice said that there have been just as many successes using adult stem cells as there have been with fetal cells, but that scientists are eager to press ahead into new areas of biomedical study just for the sake of discovery.

The Department of Health and Human Services, which oversees how federal research money is spent, is reviewing the issue of continued funding of stem cell research but has yet to indicate whether further restrictions, or an outright ban, on the use of stem cells from destroyed fetuses will be forthcoming before summer.

Bush Says A, Thompson Does B

President Bush has pledged to end federal funding of such experiments, but HHS Secretary Tommy Thompson recently said that researchers should apply for grants, because any decision will be months away.

Researchers believe that fetal stem cells have the potential to cure a range of diseases and medical conditions. However, because these cells are harvested from aborted fetuses and unwanted embryos from fertility clinics, these same scientists think Bush might bring federal funding for such research to an abrupt halt.

According to the Do No Harm, a conservative organization in Alexandria, Va., stem cell research requiring the destruction of human embryos is "objectionable on legal, ethical, and scientific grounds. Moreover, destruction of human embryonic life is unnecessary for medical progress, as alternative methods of obtaining human stem cells and of repairing and regenerating human tissue exist and continue to be developed."

Paul Maestrone, director of scientific and medical affairs for the American Parkinson's Disease Association, said the findings were first reported at a conference in Barcelona, Spain, so they came as no surprise to the Parkinson's research community.

"This was the most promising research in the field, but it did not work out the way we hoped. When you are in biomedical research, it is always a gamble. A study may work out, or it may not. In this case the procedure worked in monkeys, but not in human subjects," he told UPI.

Maestrone, who has spent more than 30 years in research, said the most promising research now for Parkinson's patients are studies involving fetal stem cell transplants. "But we are still a long way from testing the procedure in humans," he said.

Dr. Lewis Rowland, president of the Parkinson's Disease Foundation, sought to counter negative reaction to news of the study's findings in a statement to members.

"These results are disappointing to the million or more Americans and their families who live with Parkinson's disease. But the report needs to be seen in context," he said.

Although it "clearly" demonstrated that the transplant procedure is not ready for patients, but that it did "reveal some useful clues for future research, including the finding that dopamine-producing cells can take root, survive and function following a transplant. This finding is important to our overall understanding of the potential for regeneration of damaged dopamine-producing systems and has implications for future research."

He noted that "the process of scientific inquiry is a investigative journey, not a sure destination," and that "successes are always more welcome than setbacks … but even setbacks carry crucial lessons for future investigation."

Lead investigator Curt Freed told UPI the study "provided a clear demonstration that these transplants can improve clinical signs of Parkinson's in younger patients, and that the transplants grew in 85 percent of patients without immunosuppressive therapy," he said, adding equal growth was observed in older and younger patients.

Freed noted that his group has already modified its transplant strategy for studies in additional patients in the near future.

See more articles on stem cell research.

Copyright 2001 by United Press International. All rights reserved.

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