Study shows safety of Xenotransplants

Scientists are a step closer to the first pig-to-human transplant after the largest study of long-term effects found no evidence of cross-species infection. The study, published in the journal Science, was carried out by a multi-centre group led by Dr Khazal Paradis of Imutran - the Cambridge-based subsidiary of the drug giant Novartis.

The researchers retrospectively analysed peripheral blood mononuclear cells and serum of 160 patients who had received various treatments with pig tissue for evidence of porcine endogenous retrovirus. The retrovirus is integrated into the genes of modern pigs. It has been shown to infect human cells in culture, raising fears of accompanying disease from pig-to-human xenotransplantation.

Patient trials have to be approved by the UK Xenotransplantation Interim Regulatory Authority, which has announced that it will consider the research findings at its next meeting. However, Professor Robin Weiss, from University College London, appealed for caution. In an accompanying article in Science, he said that no evidence of risk could not be interpreted as evidence of no risk. He pointed out that for the community, the risk-benefit equation was much more difficult to quantify than for the individual patient.