MIAMI--Injecting fetal cells into the brains of patients with Parkinson's disease can slow down the progression of the disease, according to the first double-blind, placebo-controlled clinical study of this procedure. The study, presented yesterday at the Society for Neuroscience's annual meeting, shows that the fetal cells make up for dead brain cells, producing a neurotransmitter and thereby reducing patients' tremors and paralysis.
Parkinson's disease is marked by the death of brain cells that make the neurotransmitter dopamine. Since the 1980's, researchers have been developing a technique to replace those fetal cells destined to produce dopamine, hoping to alleviate the disease. In 1994, a team led by Curt Freed of the University of Colorado, Denver, received the first grant from the National Institutes of Health for a double-blind, placebo-controlled study of fetal cell transplants in human patients.
Forty patients with advanced Parkinson's disease underwent an operation in which a long needle was inserted in four places through the forehead, under local anesthesia. For half the patients, the needles delivered small amounts of brain tissue--derived from four human 7- to 8-week-old embryos--to the putamen, one of the brain areas affected by Parkinson's. For the other patients, the operation was a sham; nothing was injected into their brains.
One year after the operation, the latter group hadn't improved. But in the patients who had received a transplant, the fetal tissue seemed to have taken hold: Positron emission tomography scans showed a 20% or better increase in dopamine activity in the putamen in more than two-thirds of the treated patients. Patients aged 60 or younger showed a marked reduction in Parkinson's symptoms, while older patients improved only slightly compared to the controls. But even after 36 months, the transplant group was doing better than the controls, Freed reported at the meeting.
The results of the trial are "modest, but [it was] very well done," says Roy Bakay, a neurosurgeon at Emory University in Atlanta. "It's the first study, and there are going to be advances in technology that will be exponential." New techniques to help fetal cells survive the transplant should lead to more dramatic clinical benefits, he predicts.