Transplanted pig kidney works in US man's body for record 271 days
A man has lived for a record nine months with a transplanted pig kidney while waiting for a human transplant.
Transplanted pig kidney works in US man's body for record 271 days
A kidney taken from a pig functioned inside a patient for 271 days, setting a new record, according to US doctors.
Tim Andrews said the transplant gave him "hope" and saved him months of having to visit hospital so his blood could be filtered by a dialysis machine.
The team at Mass General Brigham hospital said their research shows pig organs may serve as a "bridge" until a human transplant is available.
However, the pig organ ultimately failed and was removed, meaning Andrews needed a brief period of dialysis before a donor was located.
Doctors and scientists are investigating xenotransplantation – the use of organs from other species – because of the shortage of organs for transplants.
In the US, about 100,000 people are waiting for a kidney, while only 25,000 transplants are carried out each year. More than 7,000 people in the UK are on the kidney transplant list.
Andrews was told it might take seven years to reach the top of the list, but that people survive only five years on average on dialysis.
"I had a little bit of a shortage of time… it becomes very depressing," he said.
Still, he called the idea of a pig transplant "hope" and "the light at the end of the tunnel".
"Hope is the biggest thing, the chance to be free from the [dialysis] machine and live your life."
The donor kidney had been taken from a genetically modified pig to make it suitable for human donation.
Surgeons connected the pig kidney to the blood vessels inside Tim Andrews' body so it could filter the blood.
Pigs are considered the best animal for xenotransplantation. Their organs are about the right size, and there has been years of experience raising them.
But you cannot simply go to a farm, take a kidney from a pig and place it into a person. The human body would instantly recognize the organ as foreign and mount a severe immune attack that would destroy the kidney. It would turn black within minutes as holes are torn in every cell and the organ clots from the inside.
So researchers have created Yucatan miniature pigs that have undergone 69 genomic modifications to "humanise" their organs.
These changes remove some features of pig cells that our immune system detects and attacks; add some human DNA that acts like camouflage netting to help conceal the pig tissue from the immune system; and make further tweaks that disable viruses hidden inside pig DNA to prevent infection.
Andrews had end stage kidney disease because of type 2 diabetes, and his kidneys were failing.
He was 66 when he underwent the xenotransplant on January 25, 2025.
According to details just published in the Lancet medical journal, the transplanted pig kidney worked immediately.
The kidney kept functioning for 271 days until it was removed in October that year. Tim then needed dialysis for 82 days until he received an organ from a donor in January of this year. That organ has been working well.
Dr Leonardo Riella, from the centre for transplantation sciences at Mass General Brigham, said the shortage of organs available for transplant meant "we are in a crisis".
"We are working really hard to bring hope and we truly feel that xenotransplantation can be an alternative for patients who don't have a living donor where we could potentially bypass dialysis and get them to a transplant," he said.
There were early signs that Andrews' organ was being rejected by the immune system, but this was successfully treated by adjusting his medication.
However, after about six months the blood vessels in the kidney began to be damaged and the organ became inflamed, after which it started to fail.
It is not clear exactly why, as there were no signs of antibodies attacking the pig kidney.
In their Lancet report, the doctors said: "This case illustrates both the promise and the remaining challenges of clinical kidney xenotransplantation."