Tim Andrews, 67, has become the first person to survive for nine months with a pig kidney transplant before receiving a human organ in Boston.
The New Hampshire pensioner lived with the genetically modified animal organ for a world-record 271 days, allowing doctors to use xenotransplantation as a successful bridge treatment while he waited for a human donor.
Scientists from Massachusetts General Hospital published details of the landmark medical case in The Lancet journal on Thursday, September 3, 2026. The medical team highlighted that while the individual outcome is promising, the procedure requires further study before widespread adoption.
Xenotransplantation refers to the medical practice of transplanting living cells, tissues, or organs from animal species into human patients. Massachusetts General Hospital, located in Boston, is a leading academic medical center affiliated with Harvard Medical School that has pioneered organ transplantation research.
Kidney Failure and Initial Dialysis
Mr Andrews, a father of two daughters, spent two years in severe kidney failure brought on by diabetes. Diabetes is a chronic health condition that affects how the body turns food into energy and can cause progressive damage to the blood vessels inside the kidneys.
To stay alive, he required dialysis three days a week. Dialysis is a medical procedure that filters toxins, fluids, and waste products out of the bloodstream when human kidneys can no longer perform the function naturally. The arduous routine left Mr Andrews confined to a chair for long stretches, while severe fatigue and muscle wasting stripped away his ability to walk.
Six months into his dialysis treatment, Mr Andrews suffered a heart attack as his health continued to decline. Recalling his plight, he said: "I knew I was going to die. I thought there's got to be another way."
Experimental Xenotransplantation Procedure
Determined to find an alternative, Mr Andrews searched for experimental therapies and learned about Richard Slayman. Mr Slayman, a 62-year-old from Weymouth, Massachusetts, had received a genetically modified pig kidney for end-stage kidney disease in 2024 at Massachusetts General Hospital.
Although the initial surgery succeeded, Mr Slayman died two months later from an unexpected heart problem. Attending physicians stated at the time that there was no indication his death was caused by the organ transplant.
Reflecting on the research, Mr Andrews said: "The more I read about it, the more I thought it might work." At the time, doctors across the United States had performed xenotransplantation only a handful of times.
The surgical team at Massachusetts General Hospital agreed to consider Mr Andrews for the trial on the condition that he complete several months of rigorous physical therapy. The therapy aimed to build his physical strength and lower the likelihood of rapid organ rejection.
In January 2025, Mr Andrews underwent a three-hour operation to remove his diseased kidneys and implant a pig kidney. The organ came from a Yucatan miniature pig and had been genetically altered to reduce human immune system rejection. He spent one week recovering in the hospital before being discharged on 51 different medications to prevent organ rejection. He gave the new kidney the nickname Wilma.
Record Survival and Organ Rejection
Describing his immediate recovery, Mr Andrews said: "At first it was great, which I realized was the steroids. They made you feel real good, like I'm Superman. As they wean those off, it got a little tougher. Bumps in the road."
The pig kidney successfully kept Mr Andrews off dialysis for several months, but his health began to worsen gradually. He began urinating less and developed fever, headaches, and nausea, which indicated progressive organ failure.
In October 2025, after 271 days, surgeons removed the pig kidney. Mr Andrews said: "For 271 days, we fought it and fought it and fought it. I knew probably a week before they're going to take it out, that she was done. She was done fighting."
The authors of the study in The Lancet noted that while the single case does not prove xenotransplantation will work for every patient, it demonstrates that animal organs could serve as a temporary bridge for people facing long organ waitlists.
Return to Dialysis and Waiting Lists
With no functioning kidneys remaining, Mr Andrews rejoined the 90,000 Americans currently waiting for a human kidney donation and resumed his seat in the dialysis chair. In Britain, more than 7,200 people, including 138 children, are on the kidney transplant waitlist, while only about 3,000 kidney transplants take place in the UK each year.
Describing his return to treatment, Mr Andrews said: "I was like, here I am again. I can't walk, I want to sleep all day, I'm sick all the time. [Dialysis] is tough on the body, tough on the mind."
Without working kidneys, waste products and potassium accumulate rapidly in the blood, leading to potential heart and lung failure. Although some patients survive on dialysis for years, advanced kidney disease can shorten life expectancy to months. Believing he had only months to live, Mr Andrews began making peace with his situation.
Just before midnight on January 12, 2026, almost one year after his experimental pig transplant, Mr Andrews received a phone call. Medical coordinators notified him that a near-perfect human kidney match was ready 87 miles away in Boston.
Human Donor Surgery and History of Xenotransplantation
Surgeons at Massachusetts General Hospital performed the human kidney transplant on a Wednesday morning. By Friday afternoon, Mr Andrews was discharged to continue his recovery at home in New Hampshire.
Medical attempts at xenotransplantation date back to the early 20th century, when doctors unsuccessfully tried inserting rabbit kidney tissue into a child. In the 1960s, a human patient lived for nine months with a chimpanzee kidney. By the 1990s, researchers identified pigs as the most suitable donor animals due to their physiological similarity to humans and widespread availability. Surgeons have attempted the procedure roughly a dozen times since 1900, with Mr Slayman receiving the first genetically modified pig kidney in 2024.
Speaking one month after his human organ transplant, Mr Andrews acknowledged ongoing challenges, stating: "there are still bumps" in the road.
His daily regimen has been reduced from 51 anti-rejection medications down to 20. However, he must monitor his blood sugar levels carefully because immunosuppressant drugs increase the risk of insulin resistance. Looking ahead, he added: "But I'm going to feel good."
Gratitude to Donor and Organ Donation Appeal
The human kidney came from an unidentified deceased donor. Following his operation, Mr Andrews published a message on Facebook addressed to the family of the donor.
In his message, he wrote: "I am so sorry for your loss. I grieve with you. It's got to tear you apart, but I'm here to tell you, the donation of a kidney has saved my life, and you have given hope to millions. Your family member is a hero. He's a hero, not just to me, but to the entire world. I'll never be able to repay you, but I promise you it'll be in my heart. And it will be cared and loved for for as long as I live, and I will spend my life basically preaching, and I'm not a preacher, about what this love did."
Mr Andrews said he is looking forward "to living longer than I thought I would." Recognizing that he belongs to a fortunate minority of patients, he urged members of the public to sign up as organ donors.
He said: "People should be donors. There's no reason not to have your driver's license say 'donor' on it. Mine did from the time I was 16. I didn't know I would be a recipient at that time; I thought I'd be a donor for sure, and it worked out the other way. It's an amazing feeling to have somebody save your life. It's tough because mine was a deceased, so there's a lot of emotion involved here with a person having to die for me to live. It's tough, but I'm dealing with it."
Looking to the future of medical science, Mr Andrews expressed hope that xenotransplantation will help address global organ shortages. He said: "In a few years, we could see this becoming a lot more commonplace and more and more people getting the organs they need."
