Thursday, May 13, 1999 Published at 21:15 GMT 22:15 UK
Pig clone for the millennium
It is hoped pig organs can be used for transplants
The world's first cloned pig should be born within months, say scientists in Scotland.
They hope eventually to modify the technology to make other pig clones whose organs can be transplanted into humans.
Scientists believe pigs could fill this tissue gap, provided the problems of rejection can be overcome and the dangers of transferring animal viruses to humans are eliminated.
Geron Bio-Med thinks its cloning technology is the key to producing animal tissue that is safe to use in humans.
"What you want to be able to do for xenotransplantation - for production of organs - is to remove or deactivate genes that cause immunological problems," said Simon Best, the company's Managing Director.
"Cloning is the first technology that allows you to take away genes as opposed to adding them."
However, the company, a commercial off-shoot of the Roslin Institute which produced Dolly the Sheep, says it still has some way to go before it perfects the basic cloning technology that will allow it to make a living copy of a pig.
Although the cloning research has got as far as producing embryos, none of these have survived to term in their surrogate mothers. Pigs give birth in litters of four or more and it seems the normal embryos will not accept an implanted clone.
Human stem cells
But chief scientific officer Professor Ian Wilmut, who helped to develop the cloning technology known as nuclear transfer, is hopeful of seeing cloned piglets "later this year or early in the new millennium".
"We are transferring them into recipients in order to monitor their development for the first week, but it is clear we have a lot more research still to carry out."
Geron Bio-Med is a joint venture between the scientists who cloned Dolly the Sheep and the big American biotech company Geron, which has done pioneering work in the field of stem cell technology.
Stem cells are the "master" cells for all the tissues in the body. If scientists can control the way these cells develop, they could, theoretically, grow any type of tissue they desired in the lab.
And combined with cloning, it would then be possible to create perfect-match tissue to treat people with diseases such as leukaemia.
"What we have to do is to be able to take a skin cell from a sufferer of such a disease and re-programme it so that it becomes bone marrow cells - so you can use it for your own transplant," said Best.