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April 25, 2005
The first Alzheimer's patients
to test pioneering gene therapy are proof of the treatment's
promise, say doctors.
Between 2001 and 2002, surgeons at San
Diego's University of California placed genetically modified tissue
into the brains of eight Alzheimer's patients.
It is designed to boost a naturally
occurring protein that stops cell death and stimulates cell
function.
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Now six patients are showing
signs that the implants have successfully slowed their
disease, Nature Medicine reports.
The surgeons decided they were
ready to begin trials in humans after getting promising
results in primates.
In the animals, the therapy
restored old, shrinking brain cells back to near-normal size
and quantity, as well as connections essential for
communication between the cells.
Initially, the surgeons
carried out the operation while the patients were awake but
lightly sedated.
However, two of the patients
moved as the therapy, grown from skin cells taken from the
same patients, was being injected into the brain, which
caused bleeding.
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One of these patients died five
weeks later. As a result of the bleeds, the surgeons changed
the way they carried out the operation and all of the
subsequent surgeries were performed under general
anaesthesia without any complications.
Promising signs
Professor Mark Tuszynski, the
neurologist who led the research, said their latest follow up of
these six patients suggested the treatment was working.
Memory tests suggest the gene therapy
has slowed cognitive decline by as much as 50%.
Brain scans also show that the
patients' brains are more active than before.
When they carried out a post-mortem on
the patient who died, they found some of the brain tissue that had
been dying off through Alzheimer's had started to rejuvenate.
These areas were around the sites
where the injections had been given.
Professor Tuszynski said that although
it was still relatively early days, if the findings were confirmed
it would be the first treatment that doctors had to actually prevent
cell death in people with neurological diseases.
"If validated in further clinical
trials, this would represent a substantially more effective therapy
than current treatments for Alzheimer's disease," he said.
Their studies so far have been to
check that the technique is safe.
Now that has been shown, further
studies can be done to determine how effective the treatment is.
Harriet Millward, deputy chief
executive of the Alzheimer's Research Trust, said the research was
very exciting, but cautioned that it would not be a complete cure
for Alzheimer's.
She said they were currently funding
research into drugs that mimic the action of nerve growth factor (NGF),
the name given to the gene therapy involving stimulating cell
function.
"In principle, if you can get the NGF
into the brain successfully, this could offer a way of slowing down
the decline of mental abilities in patients with Alzheimer's
disease," she said.
Professor Clive Ballard, director of
research at the Alzheimer's Society, said: "Although very
preliminary, the findings are consistent with previous studies in
animals, and offer an extremely exciting possibility of a novel
therapy.
"We very much look forward to further
studies."
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