The move is expected despite new scientific findings which have discovered that some genetic material from viruses in pigs could cross over into humans, where it might cause new diseases - or have no effect at all.
The Department of Health denied yesterday that it has delayed the publication of an advisory report, chaired by Professor Ian Kennedy of King's College London, into "xenotransplantation", which puts organs from a different species into humans.
Such transplants, using animals which have been genetically engineered not to cause tissue rejection, could ease the enormous pressure for human organ donors, who presently meet only a small percentage of demand.
David White, chief executive of Imutran, a Cambridge-based company which has produced pigs with human genes so that their organs would not be rejected when transplanted to humans, said that there is nothing to stop the company from beginning transplants to humans tomorrow. "But if we did, we would be regarded as irresponsible. We have had a request from the Government not to proceed until the Kennedy report is published, and we have agreed."
He added that almost two years ago, Imutran's research had shown the possibility of pig viruses crossing in a transplant to humans, and that it had informed the Kennedy committee and the US Food and Drug Administration. "The FDA is happy with our data, and for us to go ahead. We are really waiting for the Kennedy findings."
Suggestions of a cover-up were raised yesterday by a newspaper story which suggested that the report's publication was delayed because ministers feared that genetic material known as "retroviruses" in pigs could cross over to humans and cause as yet unknown diseases, while bypassing the body's defence systems.
But the Department of Health insisted yesterday that there has been no delay to the report's publication, following its delivery in the summer to the Secretary of State for Health, Stephen Dorrell.
"The Government will publish its report sometime in the new year, and we shall have to wait until then," said a spokesman.
One member of the Kennedy advisory group, which included experts in genetics and ethics, also insisted yesterday that the report is in favour of allowing xenotransplantation, provided adequate safeguards - including close monitoring of patients - are used.
The members are believed to have thought that using pigs' organs rather than those from monkeys or apes would reduce the risk of new diseases, because humans and pigs are further apart in evolutionary terms than primates such as baboons and chimpanzees, which are the other likely candidates for non-human organs.
Retroviruses are the genetic codings for a virus which have become incorporated into an animal's own DNA. They have no harmful effect on the animal, and are found in every cell.
But if retroviruses cross to another species, they can have unpredictable effects. HIV, which causes Aids, is a retrovirus which originally came from monkeys. Other illnesses, including forms of influenza and bacterial infections, have passed from animals to humans.
Clive Patience, of the Institute of Cancer Research (ICR), said: "Basically, we have such early data on these retroviruses that we can't predict the effect it might have on patients." But a key ICR experiment had shown that pig retroviruses could grow in human cells.Reuse content