He Lived 271 Days on a Pig Kidney. Then His Body Told Doctors It Was Time to Switch.

This account draws on reporting by CNN, Transplant News and Daily Transplant News. The HealthTech Signal has not independently interviewed Mr. Andrews.

In January 2025, Tim Andrews, a New Hampshire man on dialysis with end stage kidney disease, received a kidney from a genetically modified pig. It was one of the first such transplants attempted in a living human being outside a handful of earlier, shorter lived cases. A year later, CNN reported that Andrews was alive, and that his pig kidney had just been replaced with a human one.

He carried the pig organ for 271 days, longer than almost anyone in the history of xenotransplantation. Then his body began rejecting it, and surgeons at Massachusetts General swapped it for a human kidney from the deceased donor waitlist. Andrews is, as Transplant News put it, the first person to go "across the bridge": from a failing native kidney, to a pig kidney, to a human one, and to survive the whole sequence.

Why doctors are trying pig organs at all

The reason is brutally simple math. Roughly 90,000 Americans are waiting for a kidney transplant at any given time, and thousands die on that waitlist every year because there are not enough donated human organs. Pigs are anatomically close enough to humans that their organs have long been considered a plausible substitute, but a pig kidney transplanted unmodified into a person is destroyed by the immune system within minutes.

The breakthrough that made Andrews' case possible was gene editing. Companies including eGenesis and Revivicor have used CRISPR to knock out the pig genes that trigger the most violent human immune reactions, and to add human genes that make the organ look more familiar to a human immune system. Andrews' kidney reportedly carried more than five dozen genetic edits. That is the technical achievement: an animal organ engineered, gene by gene, to pass as human enough to survive inside one.

What "271 days" actually proves, and what it does not

I want to be precise about this, because the headlines tend to round up. Two hundred seventy one days is a genuine milestone. Earlier xenotransplant recipients, including Richard Slayman and Towana Looney, survived with pig kidneys for shorter periods, in some cases only weeks, before rejection or other complications ended the experiment. Andrews' case shows that with enough gene editing and the right immunosuppression regimen, a pig kidney can function well enough to keep a person off dialysis for the better part of a year.

What it does not prove is that xenotransplantation is ready to be a routine alternative to the waitlist. Andrews' kidney was eventually rejected. That is not a footnote, it is the headline result: even a heavily edited organ from a different species still runs into an immune wall over time. The "bridge" framing that transplant surgeons are now using, pig organ first, human organ later, is itself an admission that xenotransplants today function more like a sophisticated form of dialysis than a permanent cure.

The clinical explanation

In transplant immunology, rejection happens on a spectrum. Hyperacute rejection, within minutes, is what killed early unmodified pig organ attempts and is largely solved by today's gene edits. Acute cellular and antibody mediated rejection, over weeks to months, is what still threatens edited organs, and it is what ultimately affected Andrews' kidney. Chronic rejection, over years, has barely been studied in xenotransplants because no human recipient has lived with one long enough.

Andrews' immunosuppression regimen reportedly combined conventional anti-rejection drugs with an experimental antibody therapy targeting a costimulatory pathway, a strategy borrowed from the world of human-to-human transplant research. The fact that this combination bought 271 days, rather than 27, is the real scientific data point here. It tells researchers that the remaining barrier is manageable with better immune targeting, not that the barrier is gone.

The systemic tension: who gets to try this next

Only a small number of patients worldwide have received a pig organ: a handful of kidneys in the US, and separately, a second pig kidney recipient in China celebrated his 52nd birthday about a month after his own surgery, another sign this is becoming a small but real international field rather than a single American experiment.

Every one of these cases has so far happened under FDA compassionate use or early clinical trial authorization, reserved for patients who are otherwise out of options: too sick for the standard waitlist, or facing near certain death without an intervention. That is the honest current use case for xenotransplantation. It is not yet a queue jump for anyone waiting on dialysis. It is a last resort offered to people the existing system has already run out of road for.

The economics matter here too. A genetically edited pig kidney, produced by a company that has to breed, edit, and maintain a herd of specific pathogen free pigs under pharmaceutical grade conditions, is not going to be cheap. Whether payers, including Medicare, which covers most dialysis and transplant care in the US, will pay for xenotransplants at scale is an open question that has not been seriously tested yet, because there is no scale to test it against.

What comes next

Multiple companies now have active trials. Four living patients have received gene-edited pig kidneys under one Massachusetts General led protocol alone, according to details shared at the 2026 Transplantation Society meeting. The FDA has signaled openness to expanding these trials if the safety data holds. The real milestone the field is chasing now is not another 271 day survivor. It is a pig kidney that lasts multiple years without needing to be swapped out, because that is the point at which xenotransplantation stops being a bridge and starts being a destination.

The takeaway

Tim Andrews' story is not a cure story, and it should not be sold as one. It is a proof of concept story: gene editing can buy a dying patient real time, measured in months rather than weeks, on an organ that does not come from a human donor. That is meaningful progress in a field that spent decades barely surviving the first day. The job now is turning "bridge" into "destination," and that will take years, not months, of unglamorous immunology.