Wisconsin-based biotech company Infigen announced in February that it had cloned a litter of pigs that bring the possibility of xenotransplantation one step closer. Researchers at Infigen genetically modified the pigs to turn off two sets of genes that would result in rapid rejection of tissues by the human immune system. Researchers at University of Missouri-Columbia announced earlier in January that they had produced double knockout pigs.
Pigs possess two copies of a gene that results in the sugar molecule alpha-1-galactose being added to the surface of cells. The human immune system would spot the alpha-1-galactose molecules and launch a quick response.
Infigen researchers not only knocked out both copies of this gene, but they did so in a species of pig that was genetically modified to avoid passing on porcine endogenous retrovirus to human beings. Xenotransplantation opponents have used the risk of the exchange of retroviruses like PERV between pigs and humans to argue that such transplants are simply too risky.
Sources:
Pig-Organ Transplants for Humans One Step Closer. TheBostonChannel.Com, February 28, 2003.
DeForest firm achieves litter of cloned pigs. John Fauber, Milwaukee Journal-Sentinel, February 27, 2003.
Infigen Announces the Birth of Genetically Modified Miniature Swine for Potential Use as Organ Donors for Humans. Infigen, Press Release, February 27, 2003.
Infigen Clones Litter of Pigs for Organ Donor Use. Wisconsin Ag Connection, February 28, 2003.