A new surgical technique that bathes brain cells in a rejuvenating chemical could help roll back Parkinson's disease. A small and preliminary trial showed not only that patients can withstand the treatment but that their symptoms improve. The success could inspire similar treatments for other neurological diseases.
In Parkinson's disease, dopamine-producing neurons in certain brain areas deteriorate, hampering the ability to coordinate body movement. Most current treatments for Parkinson's disease aim to replace the lost dopamine. A decade ago, scientists discovered that a protein called glial cell-derived neurotrophic factor, or GDNF, usually found in developing brains, stimulates the growth of dopamine-producing neurons. Since then, researchers and clinicians have tried various methods of delivering GDNF to the brains of animals with Parkinson's-like disorders (ScienceNOW, 26 October 2000), but so far none had been tried in humans.
In the new work, a team led by neurosurgeon Steven Gill at the Institute of Neurosciences in Bristol, United Kingdom, and neurobiologist Clive Svendsen at the University of Wisconsin, Madison, treated five patients with Parkinson's disease. A miniature pump was implanted in the abdomen, with a tube snaking up to the brain, where a thin plastic needle dispensed GDNF to the brain cells that sustain the worst damage from the disease. After 1 year, the patients reported no serious side effects and significant--and surprising--improvements in their symptoms.
Four patients suffered fewer involuntary movements while receiving GDNF; three reported a return of lost taste and smell, which the researchers can't yet explain. Brain scans revealed increased dopamine in all patients, especially near the tip of the catheter, suggesting that the GDNF could be stimulating dopamine production, either by protecting neurons from further damage or reviving previously debilitated neurons, the team reports 31 March in the online Nature Medicine. "I'm pretty excited," Svendsen says. "It shows that GDNF at this high dose is safe."
"It's a major step forward," agrees neurobiologist Don Gash of the University of Kentucky, Lexington. "Instead of simply a drug that replaces dopamine, this actually gets at the heart of the problem, which is the degeneration of dopamine neurons." Although Gash cautions that the placebo effect cannot be ruled out at this stage, he says the technique seems promising.