Concerns over safety of xenotransplantation

A new study has prompted fresh concerns over the safety of xenotransplantation - the use of pig organs for human transplants. A team of researchers based at the Scripps Institute, La Jolla, California, found that mice given pig tissue transplants became infected with pig viruses. Their results are available on Nature's website, but have not yet been published in print.

The scientists transplanted pig pancreatic tissue into mice with weakened immune systems, and found that the mice became infected with porcine endogenous retroviruses (PERVs). The team also found that the pig-specific viruses can infect human cells grown in the laboratory. An editorial in last week's Nature claims that more independent research on potential viral risks is needed.

Dr Ron James, managing director of PPL Therapeutics, one of the firms pioneering xenotransplantation research, said last week that there were many health issues to overcome before organs suitable for human transplants could be grown in pigs. But he added that patients could be asked to remain in isolation for as long as a year following their operations, to avoid passing on unknown viruses. 'Being in isolation is better than being in a coffin' he said.

PPL has pledged to continue with its xenotransplantation research programme, despite the announcement by the UK's Roslin Institute last Monday that it is to halt its work in the same area. Professor Grahame Bulfield, director of the Roslin Institute, stressed that scientists were not abandoning projects because of new health fears. The institute's American partner, Geron Bio-Med, withdrew its funding for the xenotransplantation project last week.