Sarah Boseley, health editor The Guardian
Hopes of an
early cure for Parkinson's disease by the implantation of foetal
cells into the brain have been dashed by the devastating results
of the first full trial of the technique, which found that a number
of the patients were left with tragic side effects which cannot
be undone.
The results
of the trial will dismay Parkinson's sufferers around the world
who had hoped the controversial treatment, which has been available
in experimental form since the 1980s, might eventually spell an
end to the crippling disease.
The American
scientists who conducted the research found the therapy did not
benefit patients over the age of 60 at all. Some of the younger
patients did improve, but for 15% of those who received the implants,
the outcome was worse than the disease.
After a year
of apparently doing well, these patients began to writhe, jerk
their heads uncontrollably and throw their arms about involuntarily
as the foetal brain cells that were intended to produce dopamine,
the chemical that is depleted in Parkinson's sufferers, went into
overdrive. The cells appear to have grown too well and are producing
excessive amounts of the chemical. The scientists have no way
bringing the dopamine levels back down.
Paul Greene,
a neurologist from the Columbia University College of Physicians
and Surgeons in New York, who was one of the researchers, said
the results were "absolutely devastating" for the five
patients who cannot control their movements.
"They
chew constantly, their fingers go up and down, their wrists flex
and distend," he told the New York Times. "It was tragic,
catastrophic. And we can't selectively turn it off."
One man now
has to be fed through a tube because he can no longer eat while
another periodically becomes unintelligible during the day when
the side effects, which in his case come and go, set in.
Dr Greene
says the technique must go back to the laboratory. "No more
foetal transplants," he said. "We are absolutely and
adamantly convinced that this should be considered for research
only. And whether it should be research in people is an open question."
The shocking
results of the study are a setback for the scientists who hope
that research into stem cells - the basic cells formed by the
splitting of a fertilised human egg - may lead to cures for degenerative
brain diseases.
While scientists
cultivating stem cells will have a much clearer idea of the quality
and quantity of the material they have than those using foetal
tissue, the theory behind the implantation technique - to "seed"
the brain and encourage regeneration - is the same.
The foetal
tissue technique has not been used in the UK since an outcry over
the use of aborted foetuses put a stop to such research in the
1980s. Brain cells that produce dopamine are extracted from the
foetus and cultured. The tissue strands that result are implanted
into the areas of the brain that are supposed to produce the chemical.
The US trial
was the first to be properly controlled. Forty patients, aged
from 34 to 75, were randomly assigned to receive either the foetal
cells or nothing. To ensure that the results were due to the treatment
and not a placebo effect, all the patients underwent surgery -
four holes were drilled in the brain, whether foetal cells were
put in or not.
The outcome,
reported in the prestigious New England Journal of Medicine, will
force a rethink over the treatment.
Gerald Fischbach
who was director of the National Institute of Neurological Disorders
and Stroke which funded the study, said that this was the first
time a technique which some neurosurgeons promoted as miraculous
had been thoroughly evaluated.
"Ad hoc
reports of spectacular results can always occur," he said.
"But if you do these studies systematically, this is the
result you get."
The surgery
in the study was carried out at the University of Colorado School
of Medicine in Denver, while the evaluation was done in New York.
Robert Meadowcroft,
director of policy and research at the Parkinson's Disease Society
in the UK, said the results were disappointing but did not, in
his view, spell the end of any attempt to "seed" the
brain with either foetal cells or, in the future, stem cells.
"We need
to learn how to switch these cells off once they have done their
work," he said.
Within a couple
of years, there may be trials of techniques to implant stem cells
into the brains of people suffering from degenerative diseases
in this country, following the decision by parliament to allow
stem cell research.
Martin Edwards,
chief executive of Reneuron, a UK company working on developing
stem cell lines for medical treatment, said he believed the problem
with using foetal cells was that nobody could be sure how much
dopamine-producing tissue was being implanted.
But he said
he was convinced that scientists would eventually succeed in helping
patients with these distressing brain diseases. "There are
some upsides. The cells have survived and a proportion of patients
benefited. I interpret this with cautious optimism."
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