Cloned sheep\'s arthritis worries scientists
LONDON - Dolly, the world\'s first cloned sheep, has developed arthritis, raising fears that the cloning process may have given her a genetic defect.
The news was a setback for those who argue that cloning can become an effective - and lucrative - medical technology, but boosted the case of ethicists and animal rights campaigners who say genetic intervention is irresponsible and dangerous.
Professor Ian Wilmut of the Roslin Institute in Scotland, where Dolly was created, said on Friday she had arthritis in her left hind leg.
Arthritis is not unknown in sheep but Dolly, who in 1996 became the first mammal to be cloned from a cell taken from an adult animal, has succumbed at an unusually young age and has the disease in two joints not normally affected. This suggests it may be the result of a genetic defect caused by cloning.
\"This provides one more piece of evidence that, unfortunately, the present cloning procedures are rather inefficient,\" Wilmut told a news conference.
\"We know from our previous research that only a small proportion of embryos that we produce develop to become live offspring. Sadly, it seems one of the other outcomes from this will be that some of the cloned animals will prove to be more vulnerable to some diseases.\"
Cloning is a hot area of research because it produces animals with a pre-determined genetic make-up. Rival teams this week announced the birth of cloned, genetically engineered pigs that may be suitable for animal-to-human organ transplants.
Wilmut said it would never be known if Dolly had arthritis because she was cloned or whether it was \"an unfortunate accident\". But he urged other cloning researchers to share information to see if there was a common thread.
Some scientists believe cloned animals are prone to suffer premature ageing because cloning involves putting genes from a mature animal into an egg.
HOW OLD IS DOLLY?
Dolly was created using genetic material from a six-year-old ewe, so might arguably be said to be 11 years old, not five.
\"Scientists seem to think that they can mix and match animals\' genes in a controlled way, but actually the control is an illusion,\" said Sarah Kite, research and information director at the British Union for the Abolition of Vivisection.
\"No-one yet understands exactly how genes work or what the effects will be on the innocent animals who are subjected to biotechnology.\"
Wilmut said he was \"very disappointed\" by Dolly\'s condition but argued that further research into cloning, which has already produced hundreds of animals around the world, must go on.
\"It is a technology with enormous promise for the treatment of degenerative diseases...but we do need to be a little bit cautious,\" he said.
PPL Therapeutics Plc, which helped to produce Dolly, and a U.S. joint venture set up by Novartis AG and BioTransplant Inc have both recently cloned pigs genetically altered to make their organs compatible with humans.
Animal rights campaigners condemn such \"spare-parts\" farming, but pig kidneys, hearts and other tissue could help solve a dire shortage of donated human tissue - and create a multi-billion dollar market for successful companies.
It is a high-risk business. Shares in PPL fell 16 percent on Friday as investors took fright from news of Dolly\'s arthritis and the revelation that U.S. rivals had pipped it to the post in cloning piglets for transplants.
Some scientists think it is inevitable that human cloning will also become a reality one day, whether it is reproductive cloning to enable the infertile to become parents or therapeutic cloning to create embryos as a source of stem cells.
Wilmut said Dolly\'s problems showed that creating cloned babies would be reckless. \"I think there was already plenty of evidence that it would be completely irresponsible to think of producing a person,\" he said.
Story by Ben Hirschler, European Pharmaceuticals Correspondent
REUTERS NEWS SERVICE
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