For the first time, a pork kidney has been transplanted to a human without triggered the immediate rejection of the receptor’s immune system, a potentially important advance that could eventually help alleviate a serious shortage of human organs for transplantation.
The procedure carried out in NYU Langone Health in New York City involved the use of a pork whose genes had been altered so that their tissues no longer contain a molecule known to trigger an almost immediate rejection.
The receiver was a patient with cerebral death with signs of renal dysfunction whose family consented to the experiment before they took away the vital support, the researchers said.
For three days, the new kidney adhered to his blood vessels and remained out of his body, which allowed the researchers to access him.
The results of the testing of the transplanted kidney function “seemed quite normal,” said Dr. Robert Montgomery, surgeon of transplant, who led the study.
The kidney produced “the amount of urine would be expected” from a transplanted human kidney, he said, and there was no evidence of early and vigorous rejection that is observed when the unmodified pork kidneys are transplanted to non-human primates.
The abnormal level of creatinine of the receiver, an indicator of a deficient renal function, returned to normal after the transplant, Montgomery said.
In the United States, about 107,000 people are currently waiting for organ transplants, including more than 90,000 waiting for a kidney, according to United Network for Organ Sharing.
The waiting times for a kidney are three to five years on average.
Researchers have been working for decades on the possibility of using animal bodies for transplants, but they have been hampered on how to prevent immediate rejection by the human body.
The Montgomery team theorized to eliminate the pork gene for a carbohydrate that triggers rejection, a sugar or glucan molecule, called alpha-gal, would avoid the problem.
The genetically altered pork, called Gelsafe, was developed by the revival unit of United Therapeutics.
It was approved by the administration of US drugs and food in December 2020, for use as food for people with allergies to meat and as a potential source of human therapeutics.
Medical products developed from pigs would still require the specific approval of the FDA before being used in humans, the agency said.
Other researchers are considering whether Galsafe pigs can be sources of everything, from heart valves until skin grafts for human patients.
The NYU kidney transplant experiment should pave the path for trials in patients with end-stage renal failure, possibly in the next year or two, Montgomery said, who also received a heart transplant.
These trials could prove the focus as a short-term solution for critically ill patients until a human kidney is available, or as a permanent graft.
The current experiment involved a single transplant and the kidney was left in place only for three days, so it is likely that any future trial discover new barriers that must be overcome, Montgomery said.
Participants would probably be patients with a few chances of receiving a human kidney and a poor dialysis prognosis.
“For many of those people, the mortality rate is as high as for some cancers, and we do not think twice before using new medications and make new essays (in patients with cancer) when it could give them a couple of more lives”
, Montgomery said.
Researchers worked with specialists in medical ethics, legal and religious experts to examine the concept before asking a temporary access to a cerebral death, Montgomery said.
