In a medical first, surgeons successfully transplanted a kidney from a pig into a human being. The person’s immune system accepted the organ without triggering a negative reaction. The announcement could bring good news to the thousands of people waiting for transplant organs in the U.S. However, some people might not like the idea of sharing organs with a pig.
The procedure was completed at the NYU Langone Health Center in New York City. Doctors took a kidney from a pig whose genes had been altered so that its tissue no longer contained a molecule that leads to organ rejection.
The transplant patient was bran-dead with signs of kidney dysfunction. The family consulted with the doctors before the surgery. They eventually agreed to the experiment as an alternative to taking the patient off life support.
For three days, the new kidney lived outside of the patient’s body, giving the researchers access to it. It attached to the patient’s blood vessels to facilitate the transplant process.
Transplant surgeon Dr. Robert Montgomery told reporters that the transplant patient’s kidney function “looked pretty normal”.
The kidney made “the amount of urine that you would expect” from a transplanted human kidney, Montgomery said. He added that there’s been no evidence of organ rejection when unmodified pig kidneys are transplanted into non-human primates.
“The kidney turned a beautiful pink color and immediately urine started pouring out of the ureter,” he said. “…There was complete silence for a few minutes while we were sort of taking in what we were looking at, which was incredible. It was a kidney that was immediately functioning.”
The patient’s abnormal creatinine levels also returned to normal after the transplant, a sign their kidney function is improving.
Decades in the Making
With so many people waiting for transplant organs across the U.S., scientists have long considered the idea of using transplant organs from animals. But they were never successful because they couldn’t find a way to stop the transplant patient’s body from rejecting the organ almost immediately.
Montgomery and his team first came up with the idea of getting rid of a pig gene for a carbohydrate that often triggers the immune system. It’s a sugar molecule known as glycan, or alpha-gal.
“When you cross species with a transplant and it happens immediately, humans have pre-formed antibodies circulating in their blood that are directed towards a single molecule that was lost during evolution from pig to man,” Montgomery said. “And so, when you put an organ from a pig into a human, it’s immediately rejected.”
The genetically altered pig in question was nicknamed GalSafe. The animal was developed by United Therapeutics Corp’s (UTHR.O) Revivicor unit. It was first approved by the FDA in December of last year for use as food for people with a meat allergy and as a potential source of human therapeutics. However, the agency said any products derived from the pigs would still need specific FDA approval before they are used in humans.
While the results of the initial experiment are encouraging, the technique still has a long way to go before it becomes the new face of the country’s transplant system.
The trial included a single transplant, and the kidney was left in place for just three days, so scientists still don’t know how well the organ will work over the long term. Anyone receiving a kidney from a pig would likely be someone with few medical alternatives, such as those with low odds of receiving a human kidney and those with poor prognosis on dialysis.
“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,” Montgomery said.
He added that his team consulted with a number of medical ethicists, lawyers, and religious experts before asking for access to the brain-dead patient.
Chad Ezzell, chief clinical officer of LiveOnNY, a non-profit organization that facilitates organ and tissue donation in New York City, called the procedure an “incredible scientific achievement.”
“We are entering a new era for our field and this will give new hope to those on our waitlist as this important research moves forward,” Ezzell said.
According to the Living Kidney Donor’s Network, there are currently over 93,000 people on the transplant kidney waiting list.
“I think it will be something that, you know, eventually will be perfected to the point where it’ll be an alternative to a human organ,” Montgomery said. “…I have hope.”