Fetal Cell Implants Improve Parkinson’s Patients, Doctors Say
Eight years after President Clinton reversed the government’s funding ban on fetal tissue research, the results from the first federally funded study of fetal tissue implanted in humans--performed in patients with advanced Parkinson’s disease--show that many recipients have regained lost mobility and reduced or even stopped their medications, according to researchers.
More important, the findings demonstrate that the transplanted fetal dopamine-producing cells are still working three years after being implanted in the brain--a sign that the improvements may be long-lasting.
The results, which were presented at recent scientific meetings, are scheduled to be published in the next few months in the New England Journal of Medicine.
The study was performed by a team headed by Dr. Curt Freed of the University of Colorado Health Sciences Center, and was the first to use a control group for comparison purposes--patients who actually underwent “sham” surgery.
Other researchers, including Freed, also have performed privately funded implants, with similar encouraging results. But the use of control groups ensures that the findings are scientifically valid and not just anecdotal.
Freed said his research represents the most definitive evidence so far that experiments using these cells actually work--moving the research beyond promise and much closer to practice.
“It shows very clearly that the surgery can have powerful effects,” Freed said in an interview. “The question of whether these transplants can do anything is absolutely answered.”
Parkinson’s is a slowly progressive debilitating disease that afflicts up to 1.5 million Americans. Most are older than 60, but it is increasingly being seen in younger adults. It occurs when a certain portion of the brain is damaged or destroyed and cells there stop producing dopamine, a chemical needed by nerve cells to control muscle movement. Lack of dopamine produces tremors, muscle rigidity, poor balance and slowness of movement.
Scientists have long regarded fetal tissue research, and the emerging field of stem cell research, as holding the most promise in treating--and even curing--a variety of illnesses and conditions, including diabetes, epilepsy, Alzheimer’s disease and spinal cord injuries.
Fetal tissue is much more desirable for implantation than adult tissue because it grows more easily and rapidly when it is implanted and is less likely to be rejected by the body’s immune system. And stem cells, the parent cells from which all organs in the body are produced, are prized because they can be adapted for different cell functions.
Bush Opposes Research With Aborted Fetuses
President Bush renewed the debate over fetal and stem cell research Friday when he said he supported research using cells that come from adults and miscarriages, but not from embryos or abortions.
“I believe there are some wonderful opportunities for adult stem cell research,” Bush said. “I believe we can find stem cells from fetuses that died a natural death. And I do not support research from aborted fetuses.”
Despite his position, it is unclear whether Bush will--or legally can--do anything to stop the research. Bush could use an executive order to bar federal funding for stem cell research, or he simply could ask agency chiefs to stop the funding. Because of congressional mandates, however, he would face a higher hurdle in trying to bar further funding for fetal tissue research.
Freed’s double-blind placebo controlled study, funded by the National Institutes of Health at $900,000 annually, involved 40 patients. Half received the actual cells, and the other half underwent the phony procedure. The first operation took place in May 1995 and the last in January 1999.
In the experiments, already developed fetal brain cells that produce dopamine--soft, tiny tissue fragments no bigger than a piece of rice--are implanted into the brain.
Transplanted cells grew in 85% of the patients who received them, Freed said.
While the majority of patients receiving the cells improved, the greatest improvement was seen in those younger than 60. Also, “the results over three years have shown that the overall positive outcome of the transplant is better at three years than at one year,” he said.
Most patients were able to reduce their drug dosages substantially, and some have been able to stop medication completely, he said.
Standard Treatments Have Side Effects
There are several medications available to treat Parkinson’s, but they are not always effective and have unpredictable side effects. These include excessive, uncontrollable movement, as well as freezing spells when patients are unable to move at all.
For years patients have relied on these drugs because without them many are not able to move at all--especially before their first dose in the morning. One of the tests Freed performed on transplant recipients to assess the effectiveness of the surgery “showed a 30% improvement in the ability to move before the first dose of drugs in the morning,” he said.
What was especially dramatic, however, was the impact on patients’ quality of life. Often Parkinson’s patients must give up driving and are reluctant to be seen in public because of their inability to function.
“The social isolation from the loss of skilled movement is incredible,” Freed said.
Patients in the study found that “they didn’t have to crawl out of bed in the morning and could dress themselves,” Freed said. “Parkinson’s patients often have to have someone else button their clothes or have to use clothes with snaps. Now they can buy clothes with buttons. Patients who couldn’t before handle a knife and fork can feed themselves.”
Fourteen of the 20 patients who received the sham procedure have since returned to undergo the real surgery, Freed said.
The surgery, however, has not been perfect, and researchers are still fine-tuning it. It could be several years before it is widely available.
For example, about 15% of the patients developed excessive movements, similar to that produced by the medicines, an indication that the transplanted cells were likely overproducing dopamine.
“The amount of growth the first year was just right, but subsequent years appears to have led to a dopamine excess in some patients,” Freed said.
Researchers have refined the surgery to change the distribution of cells, using fewer cells than in earlier experiments and transplanting them into two portions of the brain, instead of one. Only one patient thus far has received surgery using the new technique; the operation took place in October, making it too early to judge its effects.
“This is a new strategy, an evolving strategy that is being developed in response to how earlier experiments have gone,” Freed said.
Federal funding for fetal tissue research was prohibited by the administrations of Ronald Reagan and the elder George Bush, but their policy was reversed by Clinton on his second day in office. Since then, the government has awarded $124 million in fetal tissue research grants.
Scientists believe that the extensive work now underway with fetal tissue will serve as an important model for future stem cell exploration.
