Signal Sent
Revolutionary neuro implant delivers key protein that counters Parkinson's
By Richard Ingham
Agence France Presse
PARIS
 An audacious form of neurosurgery, delivering a key protein to targeted parts of the brain via a tiny pump, may have delivered a remarkable blow against Parkinson's disease.
Five patients who were given the implant showed a big improvement in motor skills and quality of life and suffered no major side effects, according to a study published in Nature Medicine.
Parkinson's is a degenerative disease that affects the striatum, the part of the brain that coordinates movement. Symptoms range from tremors and awkwardness to a distinctive shuffling gait.
The disease is believed caused by cell death in the substantia nigra, a brain area that produces dopamine. As the cells die, less dopamine is produced and transported to the striatum. And without dopamine, the striatum cannot properly transmit nerve signals to the body.
There is a drug to substitute for dopamine, L-dopa, but it has side effects and as the disease progresses, the patient usually becomes less responsive to it.
Neurologists have long been tantalized by a naturally occurring protein called glial cell-line derived neurotrophic factor (GDNF), which has been shown to boost uptake of dopamine when delivered to the brain of lab rats and monkeys.
But getting GDNF into the parts of the human brain affected by Parkinson's is extremely difficult. The brain is surrounded by the blood-brain barrier, a protective membrane that filters out big molecules like GDNF.
A British-led team of doctors has taken a revolutionary approach to this delivery problem, and given convincing evidence of GDNF's promise.
They took magnetic resonance imaging (MRI) scans of the brains of five volunteers with Parkinson's and targeted those areas that seemed low in dopamine.
A pioneering surgeon, Dr. Steven Gill of Frenchay Hospital, Bristol, then inserted a slender, flexible plastic tube into their brains, positioning its tip with millimetric position on the affected area, using scanners to ensure accuracy. This catheter was then secured to the skull and connected to a tube that ran under the patient's scalp, down the neck and to a small pump placed under the skin in the abdomen, which had a supply of GDNF.
After that, "we turned the pumps on and hoped to God nothing horrible would happen, because it hadn't been done before," Clive Svendsen, a British neurologist who works at the Waisman Center Stem Cell Research Program at the University of Wisconsin, said.
"It turns out that apart from some fiddling with the concentration of the GDNF, the patients tolerated it very well and started to show effects of getting better within two to three months. The improvement came very fast."
After a year, the five recruits showed an average 39-percent improvement in motor skills, and 61-percent improvement in their quality of life. Scans showed that the targeted cells had a 28-percent increase in dopamine storage. In addition, jerky movements caused as a side effect of taking L-dopa, fell massively-by nearly two thirds.
Svendsen stressed that only small numbers were involved in the experiment and because of the cost and complexity of the surgery, the technique is unlikely to be widely adopted for the millions of Parkinson's sufferers.
Well-known victims of Parkinson's include Pope John Paul II and actor Michael J. Fox.
Also unclear, he said, are whether this treatment has enduring benefits-it is unknown whether the disease would worsen if the pumps, which deliver tiny amounts of GDNF around the clock, are turned off.
Even so, the results have been so exciting that two other groups of researchers have taken up the baton. Thirty-two patients have been enrolled in one trial, and 10 in the other.
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