On the same day the United Kingdom announced guidelines to control the practice of xenotransplantation, a British biotechnology company said that it wants to use pig livers to treat humans.
On July 30, Health Secretary Frank Dobson said that government approval will be needed for trials involving xenotransplantation. The nonstatutory UK Xenotransplantation Interim Regulatory Authority (UKXIRA) will regulate trials and will advise the government on requests until statutory rules are established. The new guidelines also give high priority to the welfare of donor animals, and the use of primates as donors will be discouraged.
"Trials in xenotransplantation involving humans will only be allowed to take place if and when we are fully satisfied that the risks associated with such procedures are acceptable," Mr. Dobson said.
Imutran, the company that hopes to give pig livers to humans, said it would follow the new guidelines, according to Reuters news service and the British Broadcasting Corporation. The pig livers would function outside a patient's body until a donor liver became available. Even if the procedure proves to be successful, Imutran has "no plans to implant the pig organ directly into the human body," the BBC reported.
To avoid rejection, Imutran has genetically modified pigs "so that their organs appear human to our immune system," the BBC said.
However, questions have been raised about the possibility of passing pig viruses to humans. Imutran is studying about 160 patients throughout the world who have received pig tissues for a variety of conditions over the past decade.
In the meantime, New Scientist reported on August 5 that UKXIRA has been presented with two studies that could allay some fears about the virus issue. In one study, by the Centers for Disease Control and Prevention, ten Swedish diabetic patients who had received pig pancreatic islet cells showed no signs of pig virus DNA or antibodies to the virus. In the other study, the Massachusetts-based company Diacrin found that none of 24 patients who had received fetal pig cells to treat Parkinson's or Huntingdon's disease had become infected with pig virus.
The BBC reported that New Scientist considered the studies "the first compelling evidence that dormant pig viruses do not spread to humans."
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