A hi-tech brain implant could transform the lives of people living with Parkinson's disease.
Scientists in Bristol have developed a system of tubes and catheters that allows them to pump protein therapy deep into patients' brains.
It is hoped the technique will encourage cells damaged by the disease to grow again.
The protein, known as glial cell line-derived neurotrophic factor (GDNF), is injected once a month through a port just behind the ear and pushed through the tubes and catheters by an external pump.
Doctors at Frenchay Hospital, Bristol, have trialled the system on six patients and are now looking for another 36 to continue the research.
Dr Kieran Breen, director of research and innovation at Parkinson's UK, said: "For years, the potential of GDNF as a treatment for Parkinson's has remained one of the great unanswered research questions.
"This new study will take us one step closer to finally answering this question once and for all.
"We believe GDNF could have the potential to unlock a new approach for treating Parkinson's that may be able to slow down and ultimately stop the progression of the condition all together.
"Currently there are very few treatments available for people with Parkinson's and none capable of stopping the condition from advancing."
Parkinson's, which affects more than 127,000 people in the UK, develops when a lack of a chemical called dopamine causes nerve cells within the brain to die.
This in turn causes symptoms such as stiffness, slowness of movement and tremors.
Previous research studies have suggested GDNF has the potential to encourage these cells to grow again - in effect stopping the progression of Parkinson's.
Tom Phipps, from Bristol, who was diagnosed with the condition eight years ago at the age of 50, was the first patient in the world to be fitted with the port system.
"I have a hope it will make a difference, if not by halting the progress of my condition then at least (allowing me to) lead a much more active life for a little bit longer," he said.
"If it doesn't affect me, it may affect, and positively affect, someone else at a later stage."
Professor Steven Gill, from Frenchay Hospital, told Sky News the equipment could be used to treat a variety of conditions.
"If this technology proves to be safe and reliable ... it has huge applications across neurological diseases, not only for treating neurodegenerative diseases like Alzheimer's and Parkinson's but also brain tumours and other conditions," he said.
The £2m project is funded by Parkinson's UK with support from The Cure Parkinson's Trust.
A foundation set up by actor Michael J Fox, who has the condition, also made a large donation.