For the first time, a pig kidney has been transplanted into a human without triggering immediate rejection by the recipient's immune system, a potentially major advance that could eventually help alleviate a dire shortage of human organs for transplant.
The procedure, performed at NYU Langone Health in New York City, involved the use of a pig whose genes had been altered so that its tissues no longer contained a molecule known to trigger almost immediate rejection.
The recipient was a brain-dead patient with signs of kidney dysfunction whose family consented to the experiment before she was due to be taken off life support, researchers told Reuters.
Test results of the transplanted kidney's function “looked pretty normal”, said transplant surgeon Dr Robert Montgomery, who led the study.
The kidney made “the amount of urine that you would expect” from a transplanted human kidney, he said, and there was no evidence of the vigorous, early rejection seen when unmodified pig kidneys are transplanted into non-human primates.
In the US, about 107,000 people are presently waiting for organ transplants, including more than 90,000 awaiting a kidney, the United Network for Organ Sharing reported. Wait times for a kidney average three to five years.
Researchers have been working for decades on the possibility of using animal organs for transplants, but have been stymied over how to prevent immediate rejection by the human body.
The genetically altered pig, called GalSafe, was approved by the US Food and Drug Administration in December 2020 for use as food for people with a meat allergy and as a potential source of human therapeutics.
Medical products developed from the pigs would still require specific FDA approval before being used in humans, the agency said.
Other researchers are considering whether GalSafe pigs can be sources of everything from heart valves to skin grafts for human patients.
The NYU kidney transplant experiment should pave the way for trials in patients with end-stage kidney failure, possibly in the next year or two, said Dr Montgomery, himself a heart transplant recipient.
Those trials might test the approach as a short-term solution for critically ill patients until a human kidney becomes available or as a permanent graft.
“For a lot of those people, the mortality rate is as high as it is for some cancers, and we don't think twice about using new drugs and doing new trials [in cancer patients] when it might give them a couple of months more of life,” Dr Montgomery said.
The researchers worked with medical ethicists, legal and religious experts to vet the concept before asking a family for temporary access to a brain-dead patient, Dr Montgomery said.