Surgeons in New York have successfully tested a pig kidney transplant in a human patient, The Guardian reports.
The patient was brain-dead, which means they were already on artificial life support with no real chance of recovering from their condition.
The kidney was from a pig that was genetically modified to prevent the organ from being recognized by the body as "foreign" and, as a result, being rejected.
The procedure, which took place at the New York University Langone Health medical centre and lasted two hours, saw the surgeons connect the donor pig kidney to the blood vessels of the brain-dead patient to see if it would function normally once placed in, or be rejected.
The kidney ultimately acted how it was supposed to do in that it filtered waste and produced urine and did not lead to a rejection.
"It had absolutely normal function," said Dr Robert Montgomery, who headed up the surgical team in September at NYU Langone Health in New York City. "It didn’t have this immediate rejection that we have worried about."
Last December, the US Food and Drug Administration gave its approval for the gene alteration in the Revivicor pigs, certifying it as safe for consumption and medicine for people.
However, the FDA require developers to submit additional documents and paperwork before pig organs can be transplanted into living humans.
"This is an important step forward in realising the promise of xenotransplantation, which will save thousands of lives each year in the not-too-distant future," said United Therapeutics’ chief executive, Martine Rothblatt.
Per BBC News, Dr Montgomery, who had himself undergone a heart transplant, said: "The traditional paradigm that someone has to die for someone else to live is never going to keep up."
He went on: "I certainly understand the concern and what I would say is that currently about 40% of patients who are waiting for a transplant die before they receive one. We use pigs as a source of food, we use pigs for medicinal uses - for valves, for medication. I think it's not that different."
