Gene Therapy Very Promising, Very Preliminary for Parkinson's
Oct. 26, 2000 -- Gene therapy for the prevention and treatment of Parkinson's disease has taken another step closer to reality, say U.S. and Swiss researchers in the Oct. 27 issue of the journal Science.
More than one million Americans have been diagnosed with Parkinson's, which causes symptoms such as trembling, rigid muscles, and loss of the ability to control voluntary movements. The disease is caused by the progressive death of nerve cells in the brain that produce a chemical called dopamine, which helps the central nervous system to control normal movements.
But as researchers from Rush-Presbyterian-St. Luke's Medical Center in Chicago and Lausanne University Medical School in Switzerland report, a new form of gene therapy can both stop the destruction of dopamine-producing nerve cells and improve control of body movement in monkeys with a syndrome similar to Parkinson's disease. The researchers used a virus engineered to be harmless and carry nerve growth factor, the gene that sparks nerve growth, into the brain.
"I think it's the most promising potential new therapy we have in the pipeline," says Parkinson's disease researcher Martha C. Bohn, MD, professor of pediatrics, molecular biology, and biological chemistry at Northwestern University in Chicago, tells WebMD.
In rats, and now in monkeys, this form of gene therapy "is very effective in protecting the dopamine [nerves] from dying, and also stimulates some regeneration. There are some unknowns, some things to work out before it goes to the clinic, but I think that a clinical trial is not too far away in this area," says Bohn, who was not involved in the study.
The therapy could be studies in humans within five years, agrees lead author Jeffrey H. Kordower, PhD. He is professor of neurological sciences and director of the Research Center for Brain Repair at Rush-Presbyterian-St. Luke's Medical Center.
And Parkinson's disease may be just the beginning, according to the author of an editorial accompanying the study. "Cocktails" of genes for various nerve growth factors could be delivered safely with these viruses to the desired areas of the brain and spinal cord to treat not just Parkinson's disease but also "an entire spectrum of other central nervous disorders," writes Lars Olson, PhD, professor of neurobiology at the Karolinska Institute in Stockholm, Sweden.
The researchers performed brain scans and other tests on the monkeys before and three months after the treatment. The growth factor appeared to not only halt the destruction of dopamine-producing nerves but also allowed dopamine production to return to near-normal levels.
Kordower and colleagues also showed that the treatment caused the growth factor to stay at high levels for at least eight months, and quite possibly longer. "We have over one-year data in rats, and there's no evidence in any study that we've done where we've ever looked and not seen it," Kordower tells WebMD.
Bohn explains that patients usually don't have symptoms of the disease until the majority of their dopamine-producing nerves are lost. So "if you can [increase the dopamine output] of the [nerves] that are left, I say that you cure the disease -- you don't replace the [nerves] they've lost, but you get rid of the symptoms."