The recommendation by the Kennedy Committee, comprising both experts in immunology and lay members of the public, will come as a serious blow to companies which had hoped to begin clinical trials with transplants of hearts and livers from genetically modified pigs into humans later this year in the United Kingdom.
The initial government response to the Kennedy Committee accepts many of its findings, although in its reply to the committee's worries about passing on diseases - notably those such as bovine spongiform encephalopathy (BSE) and new Aids-like viruses - the Department of Health's official response is understood to be that wider consultation is required.
The committee began considering the ethical and medical issues around "xenotransplantation" last year, at the same time as Cambridge-based Imutran, a private company set up by organ transplant specialists, announced that it had produced genetically modified pigs with human genes, and had transplanted organs from them into monkeys which had lived for up to two months, overcoming the normal tissue rejection problems of transplants between species.
The committee's main conclusions are that "it is not currently acceptable to move to trials involving humans, due to the lack of knowledge at the present time concerning aspects of physiology, immunology and the risk of infection". It also recommends setting up an advisory committee to oversee the development of xenotransplantation.
Research last summer suggested that pigs' DNA contains retroviruses - genetic material which could be reproduced in the human body with unpredictable affects. The resulting diseases might be devastating or harmless. The Kennedy Committee is thought to have been strongly affected by this.
In its response, the Government is expected to accept the need for an overseeing committee, and has told the committee, led by Ian Kennedy, professor of medical law and ethics at Kings College London, that it will introduce a new law to regulate xenotransplantation and so protect public health and clarify regulation issues for industry. However, it is extremely unlikely that the parliamentary timetable will allow such a law to be introduced before a general election is due in May.
The issue of the usefulness of animal organs to meet the shortfall in human donors has been a source of scientific research for decades. At least 6,000 people are awaiting transplants in the UK, and five times as many in the United States.
One of the biggest advantages of using pig organs for transplant is that they would be a plentiful source. The Kennedy Committee considered the ethical issues and decided that human needs could outweigh those of animals, though it declares that using organs from primates such as chimpanzees would come too close to taking those of humans.Reuse content