Scientists serve up the prospect of cloned pigs

Scientists who made Dolly, the world's first cloned lamb produced from an adult sheep, hope to mass-produce pigs with hearts suitable for human transplant, it emerged yesterday.

PPL Therapeutics said it planned to start research into cloning pigs in a move which could one day save millions of lives despite a moratorium on so-called xenotransplants in Britain.

Some experts fear the practice could lead to deadly viruses being introduced into humans, while others believe there are serious ethical issues at stake for medicine over mixing man and beast.

But PPL's managing director, Ron James, said he would ignore objections to the technology to meet the massive shortage in donor organs.

At the announcement of PPL's first annual results, for 1996, he said: "By the time we get around to trials, either the moratorium will have been lifted or we will be able to do them somewhere else."

PPl has already successfully created a flock of animals which have some human genes and can produce human proteins in their milk. The scientist who created Dolly has claimed human cloning is possible within two years.

Mr James said other companies were attempting to be first to develop the technology.

Unmodified pigs' hearts are already a good match for humans in terms of size and function, though they would be rejected by the host body.

Specially created animals that produce human sugars on the surfaces of their organs, however, could fool the recipient body into accepting the transplanted heart as human.

Such pigs have already been created by other companies, but PPL's technology could be used to grow ready-cloned transgenic pigs, saving a step in the production process.

Now hit-and-miss genetic engineering must be used to insert human genes into a pig cell. If the gene transplant is successful, that pig is then used to breed from normally.