http://www.timesonline.co.uk/tol/news/world/asia/article6222361.ece
May 5, 2009
Japanese scientist claims breakthrough with organ grown in sheep
Huddled at the back of her shed, bleating under a magnificent winter coat and tearing cheerfully at a bale of hay, she is possibly the answer to Japan’s chronic national shortage of organ donors: a sheep with a revolutionary secret.
Guided by one of the animal’s lab-coated creators, the visitor’s hand is led to the creature’s underbelly and towards a spot in the middle under eight inches of greasy wool. Lurking there is a spare pancreas.
If the science that put it there can be pushed further forward, Japan may be spared an ethical and practical crisis that has split medical and political opinion.
As the sheep-based chimera organ technology stands at the moment, says the man who is pioneering it, the only viable destination for the pancreas underneath his sheep would be a diabetic chimpanzee.
The organ growing on the sheep was generated from monkey stem cells but the man behind the science, Yutaka Hanazono, believes that the technology could be developed eventually to make sheep into walking organ banks for human livers, hearts, pancreases and skin.
It could happen within a decade, he guesses, perhaps two.
“We have made some very big advances here. There has historically been work on the potential of sheep as producers of human blood, but we are only slowly coming closer to the point where we can harvest sheep for human organs,” Professor Hanazono told The Times.
“We have shown that in vivo (in a living animal) creation of organs is more efficient than making them in vitro (in a test tube) but now we really need to hurry.”
The reason for Professor Hanazono’s sense of urgency — and for the entire organ harvest project being undertaken at the Jichi Medical University — lies many miles away in Tokyo and with a historical peculiarity of the Japanese legal system.
Japan defines death as the point when the heart permanently stops. The concept of brain death — the phase at which organs can most effectively be harvested from donors — does exist, but organs cannot be extracted at that point.
The long-term effect of the legal definition has been striking: organ donation in Japan is virtually nonexistent, forcing many people to travel abroad in search of transplants. In the United States, the rate of organ donors per million people is about 27; in Japan it is under 0.8.
The effect, say pediatricians, has been especially severe for children. The same law that discounts brain death as suitable circumstances for organ donation broadly prevents children under 15 from allowing their organs to be harvested.
To make matters worse, international restrictions on transplant tourism are becoming ever tougher, making Japan’s position even more untenable. To avert disaster, say doctors, Japan either needs the science of synthetic organ generation to advance faster than seems possible, or it needs a complete rethink on the Japanese definition of death.
In response to the impending crisis, and with Professor Hanazono’s sheep still very much at the experimental stage, a series of revisions to the transplant law have been proposed, but the debate has been divisive.
Taro Nakayama, the MP behind the most liberal revision — a change that would allow organs to be harvested from the brain-dead — is a former paediatrician. “Organ tourism is finished and Japan has to change its ways very quickly,” he said.
Gene genies
— In 1997 US scientist Dr Jay Vacanti grew a human ear from cartilage cells on the back of a mouse. He said he believed that it might be possible to grow knee cartilage and even a human liver
— In 2007 two scientists at the University of Nevada created a sheep with 15 per cent human cells as part of research into farming human organs from animals. Human cells were injected into a sheep’s foetus
— Last month Stelios Arcadiou, an Australian artist, unveiled an ear implanted on his arm. He planned to broadcast the sounds it would “hear” on the internet
— Last week Korean scientists said they had cloned beagles that glowed in the dark. Four puppies were created from cells injected with a gene that made them glow red under UV light
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