In a world-first, US surgeons have successfully transferred a kidney taken from a pig into a braindead human patient, in a major step towards using animal organs in human transplantations.
The team at NYU Langone Health performed the operation on a woman who was recently declared braindead, with the permission of her family. The sole object of the study, according to the lead surgeon Dr Robert Montgomery, was "to provide the first evidence that what appears to be promising results from non-human primates will translate into a good outcome in a human."
One major obstacle in making xenotransplantation possible has been the rejection of organs by hosts. To overcome this, the team used an organ from a pig that had been genetically engineered in order to remove a sugar molecule known to play a significant role in rejection. The surgeons attached the kidney to large blood vessels outside of the recipient and monitored it for two days.
“It had absolutely normal function,” Dr Robert Montgomery told the Guardian. “It didn’t have this immediate rejection that we have worried about.”
As well as not being rejected by the host, it was also able to function normally, filtering waste and producing urine. The team hopes that this initial test will lead to transplants to live hosts in the near future.
Montgomery himself has been on the other side of the knife, receiving a heart transplant three years ago. He is one of the lucky ones, with many dying on the waiting list for a new organ.
"Right now we're stuck in this paradigm, which is that someone has to die in order for someone else to live," Montgomery told Yahoo News. "And, when you think about it ... the constantly increasing need for organs for transplantation, that paradigm is not going to work. What we need is a sustainable, renewable source of organs. And that's what xenotransplantation would provide."
Pigs have similar organs to humans – with the advantage that they are comparable in size to humans as well – and are regularly raised for meat consumption, meaning that they are less likely to raise ethical concerns amongst the public than, for example, organs taken from other primates. The team chose a kidney for transplant due to the promising results seen in non-human primates, but they are hopeful that other organs would see the same success.
"If the result of xenotransplantation is satisfactory with porcine kidneys to humans then it is likely that hearts would be used with good effects in humans within a few years," Sir Terence English, the surgeon who performed the UK's first successful heart transplant in 1979, told The Telegraph in 2019. "If it works with a kidney, it will work with a heart. That will transform the issue."