Introduction to Xenotransplantation
A self-described science nerd is the latest American to get an experimental pig kidney transplant, at a crucial point in the quest to prove if animal organs really might save human lives.
The 54-year-old New Hampshire man is faring well after his June 14 operation, doctors at Massachusetts General Hospital announced Monday.
The Latest Recipient
“I really wanted to contribute to the science of it,” Bill Stewart, an athletic trainer from Dover, New Hampshire, told The Associated Press.
A self-described science nerd is the latest American to get an experimental pig kidney transplant. AP
That’s not the only milestone the Mass General team is marking: A pig kidney has kept another New Hampshire man, Tim Andrews, off dialysis for a record seven months and counting. Until now, the longest that a gene-edited pig organ transplant was known to last was 130 days.
Advancements and Trials
Based on lessons from the New Hampshire men and a handful of other one-off attempts, the Food and Drug Administration approved pig producer eGenesis to begin a rigorous study of kidney xenotransplants.
“Right now we have a bottleneck” in finding enough human organs, said Mass General kidney specialist Dr. Leonardo Riella, who will help lead the new clinical trial.
More than 100,000 people are on the U.S. transplant list, most of whom need a kidney, and thousands die waiting. As an alternative, scientists are genetically altering pigs so their organs are more humanlike, less likely to be immediately attacked and destroyed by the human immune system.
“I really wanted to contribute to the science of it,” Bill Stewart (left), an athletic trainer from Dover, New Hampshire, said. AP
Transplant surgeons Dr. Tatsuo Kawai and Dr. Alban Longchamp (from left) transplant a genetically edited pig kidney into Bill Stewart as Dr. Nahel Elias and Dr. Leonardo V. Riella watch June 14, 2025, at Massachusetts General Hospital in Boston. AP
Background and Previous Attempts
Initial experiments, two hearts and two kidneys, were short-lived and included very ill patients. Chinese researchers also recently announced a kidney xenotransplant but released little information.
Then, an Alabama woman whose pig kidney lasted 130 days before rejection prompted its removal, sending her back to dialysis, which helped researchers shift to less sick patients.
In New Hampshire, high blood pressure caused Stewart’s kidneys to fail, but he had no other health problems.
The Road to Transplantation
It can take up to seven years for people with his blood type to find a matching kidney from a deceased donor, and some would-be living donors didn’t qualify.
After two years in dialysis, he heard about Mass General’s most recent xenotransplant recipient – Andrews – and applied to be the next candidate.
“I’ve always been a little bit of a science nerd,” Stewart said. Conscious of how new these experiments are, he sought out Andrews for advice and ultimately decided, “worst case scenario, they can always take it out.”
Life After Transplantation
Thrilled to no longer have his time and energy sapped by dialysis, Stewart said he’s easing back into desk duties at work and visited his old dialysis clinic to “let everyone know I’m doing all right and maybe kind of give some people some hope.”
Riella, the kidney specialist, said Stewart had his anti-rejection drugs adjusted to counter an early concern and that Andrews has needed similar adjustments.
He said it’s far too early to predict how long pig kidneys might be able to last — but it would be useful even if initially they can buy people time off dialysis until they get a matching human organ.
As an alternative, scientists are genetically altering pigs so their organs are more humanlike, less likely to be immediately attacked and destroyed by the human immune system. AP
“A year, hopefully longer than that – that’s already a huge advantage,” he said.
Future Trials and Developments
The new eGenesis trial will provide gene-edited pig kidney transplants to 30 people age 50 or older who are on dialysis and on the transplant list.
Another developer of gene-edited pig organs, United Therapeutics, is about to start enrolling people in a similar FDA-approved study.
Conclusion
The success of these xenotransplantation trials could mark a significant turning point in the history of organ transplantation, offering new hope to thousands of people waiting for a transplant. As the trials progress and more data becomes available, the medical community will be watching closely to see if this innovative approach can provide a viable solution to the organ shortage crisis.
FAQs
- Q: What is xenotransplantation?
A: Xenotransplantation is the process of transplanting organs or tissues from one species to another, in this case, from pigs to humans. - Q: Why are scientists using pig kidneys for transplantation?
A: Scientists are genetically altering pigs to make their organs more compatible with the human immune system, potentially solving the shortage of available human organs for transplantation. - Q: How long can a pig kidney last in a human body?
A: It’s too early to predict, but even if pig kidneys can last for a year or more, they could provide a significant advantage by buying time for patients until they can receive a matching human organ. - Q: Are there any risks associated with xenotransplantation?
A: Yes, as with any transplant, there are risks of rejection and other complications. However, the use of gene-edited pig organs is designed to minimize these risks. - Q: When will xenotransplantation become a standard medical practice?
A: The timeline depends on the success of ongoing and future clinical trials. If these trials demonstrate the safety and efficacy of xenotransplantation, it could become a more common practice in the years to come.
