Transplanted pig kidney works in US man’s body for record 271 days

A Pig Kidney Kept a Man Alive for Nine Months — and Pointed Toward a Future for Organ Transplants

Constantvpn.com – A genetically engineered pig kidney sustained a 66-year-old American patient for 271 days, setting a new record for how long a xenograft organ has functioned inside a human body. The milestone, detailed in a paper published in the journal The Lancet, marks the longest continuous operation of a non-human kidney to date and intensifies debate over whether cross-species organ donation can become a practical lifeline for patients trapped on waiting lists.

The recipient, Tim Andrews, underwent the procedure on January 25, 2025, at Mass General Brigham hospital in Boston. His kidneys had failed as a consequence of type 2 diabetes, leaving him dependent on regular dialysis sessions to filter waste from his blood. By the time surgeons attached the porcine organ to his internal vasculature, Andrews had been told he might face up to seven years at the bottom of the transplant queue — a span that, on average, exceeds the five years most dialysis patients survive.

“I had a little bit of a shortage of time… it becomes very depressing,” Andrews recalled. “But the idea of a pig transplant was hope — 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 Science Behind the Swap

Xenotransplantation — the transfer of organs between species — has long been constrained by the human immune system’s ferocious response to foreign tissue. Without intervention, a pig kidney placed inside a person would be recognized as alien within minutes. Immune cells would swarm the graft, rupturing cell membranes and triggering internal clotting until the organ turned black and ceased functioning.

To overcome that barrier, researchers have turned to Yucatan miniature pigs carrying 69 distinct genomic edits. These modifications serve three purposes: they eliminate surface markers on pig cells that human antibodies readily target; they insert segments of human DNA that act as a kind of biological camouflage, making the tissue less conspicuous to the recipient’s immune surveillance; and they silence latent viral sequences embedded in pig genomes that could otherwise reactivate and cause infection after transplantation.

Pigs occupy a unique niche in this field. Their organs approximate human size, decades of agricultural practice have produced deep expertise in their husbandry, and their reproductive biology allows relatively rapid scaling of donor supply compared with primates.

What Happened Inside Andrews’ Body

The transplanted kidney began filtering blood immediately after surgery. For roughly six months it performed its role, though clinicians noted early indicators of immune rejection that were managed by adjusting Andrews’ immunosuppressive medication regimen. Around the six-month mark, however, the organ’s blood vessels sustained progressive damage. Inflammation set in, function declined, and by October 2025 the kidney was removed.

What remains puzzling is the precise mechanism of failure. No circulating antibodies directed against the porcine tissue were detected, leaving the team without a straightforward immunological explanation for the vascular injury and subsequent organ breakdown.

Following removal, Andrews required 82 days of dialysis before a human donor kidney became available. That human organ, received in January of the following year, has been functioning well.

A Bridge, Not a Destination

Dr Leonardo Riella, of the Centre for Transplantation Sciences at Mass General Brigham, framed the case not as a cure but as a stopgap strategy. With roughly 100,000 Americans awaiting a kidney while only about 25,000 transplants are performed annually, and more than 7,000 patients on the UK kidney waiting list, the supply gap is acute.

“We are in a crisis,” Riella said. “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.”

In that framing, the pig kidney’s role is to buy time — to keep a patient alive and out of the dialysis chair while they wait for a compatible human organ. The 271-day window achieved in Andrews’ case demonstrates that such a bridge is clinically feasible, even if the graft ultimately cannot serve as a permanent solution.

What Comes Next

The Lancet authors close their report with a measured assessment:

“This case illustrates both the promise and the remaining challenges of clinical kidney xenotransplantation.”

That tension — between genuine biological progress and unresolved questions about long-term graft survival, vascular integrity, and immune tolerance — defines the next phase of the field. If future protocols can extend the functional lifespan of a xenograft kidney well beyond nine months, or if paired with refined immunosuppression that prevents the vascular damage observed here, the technology could reshape how transplant centres manage patients who would otherwise face years of dialysis or death. For now, the record stands at 271 days: a number that, while short of a permanent cure, represents the longest a non-human kidney has ever kept a human alive.