Firm attacked over 'breakthrough' in pig donor organs

Leading scientists have criticised a British biotechnology company for publicly claiming to have made a breakthrough in the cloning of genetically engineered pigs to supply organs for human transplants.

PPL Therapeutics announced yesterday that it had produced the first cloned pigs with two genes "knocked out" to prevent tissue rejection after a pig-to-human organ transplant.

It said the research was another "key milestone" for the company and demonstrated its "leading-edge position" in the rapidly developing field of cloning animals for organ transplants.

The Royal Society questioned the research because it has not yet been subjected to the usual process of peer review, under which it is assessed by independent experts before being published by a scientific journal.

The company is running low on cash and is expected to try to raise new funds from shareholders early next year. It has just £17m in the bank and, at the current rate of losses, will be out of money by the end of next year.

Professor Patrick Bateson, vice-president of the Royal Society, suggested that while the publicity might boost the company's finances it did not meet the strict criteria for the publication of scientific results. "The scientific community will be sceptical about this so-called breakthrough until the work has been subjected to rigorous peer review by other researchers in the field," Professor Bateson said.

"This announcement, which no doubt will boost the company's share price, could be considered premature before other scientists have had a chance to look at the claims.

"There remains a large number of clinical, safety and regulatory issues, not to mention public acceptance, which would need to be addressed before we could start to transplant animal organs into humans," he said.

A spokeswoman for the company defended the decision on the grounds that the information was price-sensitive and that under the rules of the Stock Exchange all companies are encouraged to publish such information as soon as possible.

PPL Therapeutics said four healthy cloned piglets with a double knock-out gene were born at its American subsidiary on 25 July. A fifth piglet had died of unknown causes.

All four pigs are missing a working version of both genes for alpha galactose, an enzyme that adds a sugar molecule to the surface of pig cells. This sugar plays a critical role in the "hyperacute" tissue rejection when organs are transferred from one species into another.

"The ability to delete or 'knock out' both copies of the gene, therefore, provides a vital step in producing pigs with organs and cells which can be used in humans," the company said.

David Ayares, vice-president of research at PPL's American subsidiary, said: "This advantage brings us closer to the promise of a potential solution to the worldwide shortage of organs and cells for transplantation."

Professor John Fabre, a liver specialist at Guy's, King's and St Thomas' School of Medicine in London, said: "While scientifically exciting, the clinical relevance has been greatly overstated. It is likely that unacceptably high doses of immunosuppressive drugs would be needed to prevent rejection, even for a few months."