New York, New York - US surgeons who transplanted a genetically modified pig kidney into a brain-dead patient said Wednesday the organ was still working well after a record 32 days!

"We have a genetically edited pig kidney surviving for over a month in a human," Robert Montgomery, director of the New York University Langone Transplant Institute, told reporters.

"I think there's a very compelling story that exists at this point that I think should give further assurances about starting some initial studies... in living humans."

More than 103,000 people are waiting for organs in the United States, 88,000 of whom need a kidney, making this latest development potentially very significant.

Unlike previous transplants, which involved body parts with up to 10 genetic modifications, the latest had just one.

By "knocking out" the gene responsible for a biomolecule called alpha-gal – a prime target for roving human antibodies – the NYU Langone team were able to stop immediate rejection.

"We've now gathered more evidence to show that, at least in kidneys, just eliminating the gene that triggers a hyperacute rejection may be enough along with clinically approved immunosuppressive drugs to successfully manage the transplant in a human for optimal performance – potentially in the long-term," said Montgomery.

Surgeons also embedded the pig's thymus gland, which is responsible for educating the immune system. Adam Griesemer, of the NYU Grossman School of Medicine, added that this practice allowed immune cells in the host's body to learn to recognize the pig's cells as its own, preventing a delayed rejection.

Monitoring showed that levels of creatinine, a waste product, were at optimal levels, and there was no evidence of rejection.

Crucially, no evidence of porcine cytomegalovirus – which may trigger organ failure – have been detected since the transplant. The team plans to continue monitoring for another month.

This latest experimental procedure is part of a growing field of research aimed at advancing cross-species transplants, testing the technique on bodies that have been donated for science.

The research was made possible by the family of the 57-year-old male patient, Maurice "Mo" Miller, who was found unresponsive in his bathroom in July. Doctors determined he had an aggressive form of brain cancer, and would not wake up.

"Though my brother cannot be here, I can say with confidence he would be proud of the fact in the tragedy of his death, his legacy will be helping many people live," his sister Mary Miller-Duffy told reporters.

In January 2022, surgeons at the University of Maryland Medical School carried out the world's first pig-to-human transplant on a living patient.

The patient, who received the pig heart, died two months later. His death was blamed on a pig virus.

The donor pigs in these experiments are from a herd from Virginia-based biotech company Revivicor.

The Food and Drug Administration approved the herd as a source of meat for people with hypersensitivity to the alpha-gal molecule, an allergy caused by tick bites.

Current so-called xenotransplantation research efforts focus on pigs, which are thought to be ideal donors for humans because of their organ size, their rapid growth, and large litters, as well as the fact they're already raised as a food source.