Published in The Australian in Sydney Australia today.
Porcine transplants for Parkinson's may be in jeopardy.
Disease fears end pig organ transplants
By JAMIE WALKER in London and SARAH STOCK
15aug00
The cloning pioneers who developed Dolly the sheep are withdrawing from
controversial research using pigs over fears that new diseases could be
passed on to humans through the use of transplanted animal organs.
The decision comes just days ahead of an expected move by the British
Government to cautiously endorse the use of human embryos in so-called
"therapeutic cloning".
Researchers working at the Roslin Institute near Edinburgh, Scotland, had
been working on techniques to rid pigs of specific genes so that human
immune systems would not reject their organs.
But research team head Ian Wilmut said yesterday that the risk of
unleashing potentially deadly new viral diseases on the population was too
great.
"We are reducing pig work," Dr Wilmut said. "It has not quite finished, but
it will be before long.
"I think the concern is mainly unknown viruses. If you know what the
disease is, you know what to look for."
The ending of the Roslin research program throws into question the future
of other projects aimed at clearing the way for pig-to-human transplants,
seen as a potential solution to the chronic shortage of donor organs.
However, Australian scientists said yesterday they would press ahead with
research into pig transplants in humans. It is understood Sydney
researchers, investigating whether pig viruses are transmitted to animals
with weak immune systems via transplants, are confident no such
transmission occurs.
The results of their study will be published in an international scientific
journal at the end of the month.
Bernie Tuch, director of the Pancreas Transplant Unit at Sydney's Prince of
Wales Hospital, said the risk of viral transmission could never be ruled
out completely. But Professor Tuch said a study published in the journal,
Science, last August found no evidence of pig-virus infection in 160 people
worldwide who had been treated with pig tissue.
Doctors pushing for pig-tissue transplants have always argued infection
risks could be reduced by breeding special virus-free herds. But a British
study in 1997 showed that pigs had viruses incorporated into their DNA that
were able to infect human cells.
Known as PERVs, they are retroviruses, a class that includes HIV.
And because they are part of the pig's genetic make-up, they cannot be bred
out. Two of the most dangerous recent diseases - HIV and CJD, the human
variant of "mad cow disease" - both appear to have come from animals.
Scientists have been concentrating on pigs because they are a close genetic
match to humans.
The co-founder of the Imutran program, David White, who helped develop the
first genetically modified pig with a human-compatible heart, said last
night he was very disappointed by the Roslin decision.
"The technology Ian Wilmut and his group developed is a major advance and I
think the question of safety issues can be resolved," he said.
The British Government is expected to publish tomorrow a report by the
Chief Medical Officer, Liam Donaldson, giving the all-clear to very limited
use of human embryos for cloning research, another potential source of
transplant organs.
The final decision, however, will be left to a free vote of MPs.
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