How are scientists trying to prevent hyperacute rejection of xenotransplants?
In 1992, British scientists succeeded in breeding a pig, called Astrid, with human ‘flags’ on her cells. They put genes (DNA) for the human flags into pig embryos and put them into the wombs of surrogate sows. They had to do it many times before Astrid was born. She was still a pig, but she was a ‘transgenic’ pig and her DNA was 0.000001% more human than other pigs. Since 1992, herds of transgenic pigs have been bred in Europe and the USA which have human flags on their cells. But traditional breeding methods mean that some animals have plenty of flags while others don’t. It’s very hit and miss. However, US scientists are very close to cloning piglets which have human flags on their cells. So they should soon have a reliable source of transgenic pig organs.
