A kidney transplanted from a genetically modified pig has functioned for 271 days in the body of an American patient, setting a new record for the duration of such an organ's functioning in a human.
Tim Andrews, who suffered from end-stage kidney disease, said the transplant gave him "hope" and freed him for several months from dialysis, a procedure through which blood is filtered with the help of a machine.
Andrews underwent the transplant on January 25, 2025, when he was 66 years old. The pig kidney began functioning immediately after the procedure and continued to work for 271 days, until October of the same year, when doctors decided to remove it.
After the organ was removed, the patient returned to dialysis for 82 days, until January, when a human donor was found. The transplanted kidney from this donor is reportedly functioning well.
The case is considered by doctors to be an important step in the development of xenotransplantation, a process that aims to use animal organs for transplantation into humans.
Researchers hope that in the future such organs could serve as a "bridge" for patients waiting for a human organ, reducing the time they have to spend on dialysis.
Doctors at Mass General Brigham say the shortage of organs for transplant has created a serious crisis. Xenotransplantation could become an alternative for patients who do not have a living donor and face years of waiting.
In the United States alone, about 100,000 people are waiting for a kidney transplant, while only about 25,000 transplants are performed each year. In the United Kingdom, more than 7,000 people are on the waiting list.
Andrews was informed that he could have to wait about seven years to reach the top of the transplant list, while the average life expectancy for dialysis patients is about five years.
"I was a little short on time... it gets very depressing," Andrews said, describing the pig transplant as "hopeful" and a "light at the end of the tunnel."
"Hope is the greatest thing, the chance to get off the dialysis machine and live your life," he said.
Why are pig organs used?
Pigs are considered among the most suitable animals for xenotransplantation, as their organs are similar in size to those of humans and there is a long experience in breeding them.
However, a regular pig organ cannot be transplanted directly into a human, as the immune system would identify it as foreign and cause a strong rejection reaction.
To overcome this obstacle, scientists have developed genetically modified Yucatan miniature pigs. The pig from which Andrews' transplanted kidney was taken had undergone 69 genomic modifications.
The changes aim to eliminate certain characteristics of pig cells that provoke a human immune system reaction, add human DNA to make the organ more acceptable to the body, and deactivate certain viruses present in the pig DNA.
However, Andrews' transplanted kidney did not work permanently. During the first few months, signs of rejection by the immune system appeared, which were successfully treated with a change in medication.
After about six months, the kidney's blood vessels began to become damaged. The organ became inflamed and gradually began to lose function, forcing doctors to remove it.
The exact cause of the damage still remains unclear, as tests did not reveal any signs of antibodies directly attacking the pig's kidney.
Despite the experiment ending after 271 days, the case is considered a significant development in efforts to use animal organs as a potential solution to the global shortage of organs for transplantation.
