A Pig Kidney Kept This Man Alive for Nine Months, Then He Got a Human One
Finn's Take· TL;DR- Genetically modified pig kidney kept patient alive for 271 days without dialysis, shattering previous survival records and offering hope to 90,000 Americans waiting for transplants.
- Sixty-nine genomic modifications prevented immune rejection by removing pig features, adding human DNA, and disabling pig viruses, with no pig pathogens detected during the trial.
- Pig kidneys could serve as temporary bridges keeping critically ill patients alive until human donor organs become available, potentially approved for widespread use within 5-10 years.
A Record-Breaking Transplant That Could Change Everything
Tim Andrews of New Hampshire didn't know it at the time, but when he received a genetically edited pig kidney on January 25, 2025, he was about to set a medical record that would reshape the future of organ transplantation. Andrews successfully lived with the genetically edited kidney for 271 days — during which he did not need dialysis — before receiving a human kidney from a donor. His case, published in The Lancet medical journal , offers hope to the hundreds of thousands of people around the world whose kidneys have failed.
Andrews, a 66-year-old patient experiencing end-stage kidney disease caused by type 2 diabetes, received the experimental organ at Massachusetts General Hospital. Before the surgery, his outlook was grim. According to the transplant team, Andrews had just a 9% chance of receiving a human kidney in the next five years, and a nearly 50% chance of being removed from the transplant wait list because of his deteriorating health. The pig kidney didn't just extend his life — it gave it back to him. Andrews described the pig kidney transplant as a "miracle," adding that he was able to cook, vacuum, and take long walks with his dog, Cupcake.
How a Pig Kidney Works Inside a Human Body
Transplanting unmodified animal tissue into a human triggers an immediate, aggressive immune response that destroys the organ within minutes. To prevent this, the donor kidney used in Andrews' case underwent 69 genomic modifications. These laboratory alterations removed specific pig cell features that normally attract human immune attacks, inserted human DNA segments to disguise the tissue, and disabled viruses hidden within the pig genome.
The first pig kidney transplant into a living person, in 2024, ended after 52 days when the patient died from unrelated heart problems, and no previous studies had documented xenograft survival beyond two months. Andrews shattered that record. After roughly six months, damage developed in the pig kidney's blood vessels which progressed to organ failure and the kidney was removed nine months after transplantation. After several months back on dialysis, Andrews received a kidney from a dead human donor, which worked well during six months of follow-up. There were no new antibodies against human tissue detected, indicating the pig kidney had not made it harder for the human kidney transplant to work successfully. Crucially, no pig viruses or other pig pathogens were detected at any point.
The Crisis Driving This Science Forward
The urgency behind this research is staggering. Over 90,000 people in the U.S. are waiting for a kidney transplant. Around 12 of those people die every day waiting for a kidney transplant. Lead author Dr. Leonardo Riella put it plainly: "The organ shortage is the greatest crisis we have right now in transplantation."
Two companies have received FDA approval to conduct clinical trials transplanting genetically modified pig kidneys into patients with kidney failure: United Therapeutics and eGenesis. The EXPAND study is a multicenter, open-label clinical trial sponsored by United Therapeutics, evaluating the UKidney — a 10-gene-edited pig kidney — in patients with end-stage renal disease who are ineligible for or unlikely to receive a human donor kidney within five years. If results in the first six patients are promising, the company has clearance to expand the trial to up to 50 patients.
A Bridge, Not Just a Backup
Andrews' case is the first known instance in which a pig kidney was used as a temporary bridge until a human organ became available. That framing matters enormously. Rather than replacing human donors entirely, pig kidneys could keep critically ill patients alive and off dialysis long enough to reach the top of the transplant list — a lifeline for those who might otherwise never make it. Experts are hopeful the treatment will be approved within the next 5 to 10 years.
Andrews' story is both a personal triumph and a scientific proof of concept. Decades of research, gene-editing breakthroughs, and the courage of a handful of patients have brought medicine to the edge of something transformative. The question is no longer whether pig organs can work inside a human body — it's how soon this option can reach the tens of thousands of people still waiting for their chance.