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Fetal Cell Transplant Therapy for Parkinson's Now Doubted

The effectiveness of fetal cell transplants as a treatment for Parkinson's disease is facing serious questions. The latest study showed some patients suffered serious and irreversible side effects. Dr. Curt Freed of the University Colorado Health and Science Center headed the study and is in Denver to talk to us this morning.

The latest study on transplanting fetal brain cells into patients with Parkinson's disease had mixed to disappointing results. Although there was evidence that the cells grew, there was no benefit for older patients. And although some younger patients reported feeling better, 15% suffered serious irreversible side effects. Freed headed the study and defends the results. He says that this approach is promising and there is need for this research to continue.

Previous research into fetal cell transplantation for Parkinson's patients had shown that many seemed to feel better and some symptoms were alleviated by the procedure. But new research published this week's issue of the New England Journal of Medicine is not so positive.

Researchers concluded that the transplants survive in patients with severe Parkinson's disease and that they result in some clinical benefit for younger but not older patients. Researchers also noted a disturbing side effect in some younger patients who had the treatment. In a year or so, they developed twitching and exaggerated symptoms known as "disabling dyskinesias." These side effects are common with the current drug treatments and usually taking the patients off the drug makes the symptoms go away. With the cell transplant the dyskinesias are permanent.

An article in the New York Times quoted one of the study authors, Green, as saying these results were "devastating" and "horrifying." Others say that unknown side effects are a danger in any experimental treatment and that part of the clinical trial process involves a certain amount of risk despite the regimented phases and rigid scientific safety protocols involved. Green said that he believed we should step back to doing tests in lab animals until we understand this well.

In the study, researchers randomly assigned 40 patients who were between the ages of 34 and 75 years and had severe Parkinson's disease. The patients either received a transplant of embryonic neurons into the brain or underwent a sham surgery that consisted of just drilling holes into the skull.

The study had stirred controversy previously because it was a double blind procedure that required some of the patients to undergo a placebo surgery: Holes were drilled in the skull but no treatment was given. Still, the treatment was in such high demand among patients that even those who participated and were found to have undergone a "sham" surgery were offered a chance of having the real thing afterward.

The latest study doesn't reveal whether the real treatment is more effective than sham surgery: Many patients said they felt btter after the placebo surgery.

Interview with Dr. Curt Freed

What kind of side effects did the patients have?

Fifteen percent had excess movements even after they stopped taking the drugs. In other words their brains were still producing dopamine.

Many other researchers were "horrified" and called the results "devastating," yet you say the outcome was positive?

We look at this as a step toward new treatments for Parkinson's disease. These side effects can be controlled by putting a stimulator in the brain and that has been done in some patients. But obviously the procedure needs modification before it can be used as a treatment.

Most other studies have shown that using stem cells have made Parkinson's patients better. How do you explain your results?

All studies have a range of resuts. Some patients don't respond, some respond well, and some over-respond. Our study had that range, too.

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