Parkinson's patients have tubes placed in brain in protein study
People with Parkinson’s disease have been fitted with an implant that can deliver drugs directly to the brain through a port in the side of their head, in a pioneering study.
The device was used to send a naturally occurring protein, which it is hoped may help restore cells damaged by the disease, to an affected part of the brain.
The results of the trial offer hope to patients with Parkinson’s, the researchers say. Meanwhile, the effectiveness of the delivery system suggests it could offer new ways of treating brain tumours, strokes and other degenerative conditions.
A total of 41 people underwent robotic surgery to have four tubes placed in their brains as part of the study, funded by Parkinson’s UK and carried out in association with North Bristol NHS trust.
The system allowed a protein, glial cell line-derived neurotrophic factor (GDNF), to be sent to the affected part of the brain with pinpoint accuracy.
Half of the group received monthly infusions of GDNF over a period of nine months, while the other half received placebo infusions. All participants were then offered a nine-month course of GDNF.
Both groups of patients showed improvements in their symptoms after nine months, particularly those who had received GDNF, but there was no significant difference between the two, according to the findings published in journal Brain and the Journal of Parkinson’s Disease.
After 18 months, when all patients had received GDNF, both groups showed moderate-to-large improvements in their symptoms, with many becoming more active and taking up pursuits such as cycling.
However, the brain scans of patients who received the protein showed signs of improvement after the first stage of the trial, the researchers said.
Dr Alan Whone, principal investigator, said patients had on average been diagnosed eight years previously but the scans showed images that would be expected two years post-diagnosis.
“We’ve shown with the Pet [positron emission tomography] scans that having arrived, the drug then engages with its target, dopamine nerve endings, and appears to help damaged cells regenerate or have a biological response,” Whone said.
The improvement in brain scans was “beyond anything seen previously in trials of surgically delivered growthfactor treatments for Parkinson’s,” Whone said. “Its failure to produce the same effect on symptoms could be for a number of reasons.
“It may be that the effects on symptoms lag behind the improvement in the brain scans, so a longer doubleblind trial may have produced a clearer effect. It’s also possible that a higher dose of GDNF would have been more effective, or that participants at an earlier stage of the condition would have responded better.”
Prof Steven Gill, the neurosurgeon who designed the implant, said it was the first time it had been used in a trial. He believes the technology could be used to administer chemotherapy to brain tumour patients or to test new drugs for Alzheimer’s and stroke patients.
“This trial has shown that we can safely and repeatedly infuse drugs directly into patient’s brains over months or years through a small implanted port that emerges through the skin behind the ear,” Gill said.
“This is a significant breakthrough in our ability to treat neurological conditions such as Parkinson’s because most drugs that might work cannot cross from the bloodstream into the brain due to a natural protective bar