🐷 Picture a pig's kidney filtering the blood of a living patient in a hospital in Sapporo. That scene is now penciled in for early 2028. A Japanese startup says it will run the country's first clinical trial of pig-to-human kidney transplants at two hospitals, betting that organs grown from US-engineered pigs can start chipping away at one of the worst organ shortages in the developed world.

Two hospitals, a 2028 start

On June 29, PorMedTec, a venture spun out of Meiji University and based in Kawasaki, said it had agreed with two hospitals to prepare for Japan's first xenotransplantation trial: Hokkaido University Hospital in Sapporo and Shonan Kamakura General Hospital near Tokyo. The plan is to file with the Pharmaceuticals and Medical Devices Agency (PMDA, Japan's drug regulator) by the end of fiscal 2026 and begin transplanting as early as the start of 2028.

The trial will be small and deliberately cautious. Each hospital expects to handle only a few cases, with the first goal being safety. Effectiveness will be judged against a concrete bar: keeping the patient off dialysis for at least about half a year, or 24 weeks. Candidates are people with chronic kidney failure who have no relative able to donate, who are in their 50s or 60s, and who don't have serious complications such as heart disease. Because recipients will be on stronger immunosuppressant drugs than usual, doctors will weigh their overall health carefully before enrolling them.

The logistics are being handled with the same care. Each hospital will have a facility to remove the organ from the donor pig on site or right next door, so the kidney can reach the operating room with almost no delay and in the best possible condition.

Why Japan, of all places, needs this

Japan is, by some measures, a dialysis superpower. Around 340,000 people are on dialysis, one of the highest rates per capita anywhere. The treatment works, but it is grueling: typically three sessions a week, several hours each, for the rest of a patient's life unless a transplant comes. It is expensive, too. Caring for one dialysis patient costs the health system roughly 5 million yen (about $31,000) a year, and the national total is estimated at around 1.6 trillion yen, several percent of all medical spending.

And yet a transplant, the one treatment that can free patients from the machine, is almost out of reach. About 14,000 people are registered and waiting for a kidney from a deceased donor, but only around 200 such transplants happen each year, fewer than two in a hundred. The average wait stretches to roughly 15 years. For comparison, deceased-donor rates run near 44 per million people in the United States and 46 in Spain; in Japan, by international comparisons, the rate is below one. Close to nine in ten kidney transplants here come from living donors, usually family members, a pattern shaped by history and by attitudes toward death and the body.

That gap is what xenotransplantation is meant to fill. PorMedTec's chief scientist, Meiji University professor Hiroshi Nagashima, has said the company wants to build on the achievements of the world-leading US groups and lay the groundwork for practical xenotransplantation in Japan.

Turning a pig into a donor

Pigs sit at the center of this field partly for practical reasons: their organs are close to humans in size and function. The obstacle has always been the immune system. The human body recognizes certain sugar molecules on pig cells as foreign and attacks them within minutes, a reaction that wrecked early attempts.

Gene editing changed the math. PorMedTec works with eGenesis, a Massachusetts biotech, using the company's cells to breed cloned pigs whose DNA has been altered in about ten places: removing the markers that trigger rejection and adding human genes that calm the immune response. eGenesis has also switched off the pig's endogenous retroviruses, viral sequences built into the pig genome that researchers worry could, in theory, infect a human recipient. The company has reported in Nature that a monkey lived more than two years on one of these kidneys.

The pigs will be raised under near-sterile conditions. PorMedTec plans to start producing trial pigs in July 2026 and to build capacity for about 100 donor pigs a year by 2027, with a new breeding site in Kyoto and the organ-removal facilities in Sapporo and Kamakura.

What the United States has already shown

Japan is following, not leading, and the company is candid about that. The US and China are ahead; between them they have performed eight pig-kidney cases in humans, according to Japanese reporting, and the results have begun to look real rather than experimental.

The clearest sign came from eGenesis itself. A US patient who received one of its pig kidneys in November 2025 had gone 31 weeks without dialysis as of late June 2026, the company says. An earlier eGenesis recipient, transplanted at Massachusetts General Hospital in early 2025, became the longest-surviving person with a pig organ and, that summer, threw out a ceremonial first pitch at a Boston Red Sox game. In another US case, a kidney-failure patient spent 38 weeks off dialysis on a pig organ before receiving a human kidney, exactly the role xenotransplantation is partly designed to play: a bridge that keeps someone healthy until a human organ arrives.

The other US heavyweight, United Therapeutics, began its own FDA-cleared trial in late 2025, transplanting its ten-gene-edited "UKidney" into a first patient at NYU Langone Health, with a cohort of six planned. Both US programs, like Japan's, treat the 24-week mark as a key milestone.

None of this is risk-free, and the field has the failures to prove it. In one widely reported US case, a pig kidney that had set the survival record at the time eventually had to be removed, and the patient returned to dialysis. Surgeons describe dialysis as a "lifeboat" here: if the organ fails, the patient can go back on the machine and recover. That is part of why the kidney, and not the heart, has become the proving ground.

The questions that won't go away

Three hard issues travel with every xenotransplant. The first is infection: even with retroviruses switched off, regulators will watch for any pathogen crossing from pig to human. The second is long-term rejection, which is why recipients face heavier immune suppression and its side effects. The third isn't medical at all. Pigs are bred and killed specifically to supply organs, and not everyone is comfortable with that, just as not everyone is at ease receiving an animal organ in the first place. Building public trust through open discussion, rather than a low-profile rollout, is something Japanese researchers themselves say matters.

If the trial clears its hurdles, PorMedTec plans to apply in 2029 to have the pig kidney approved as a regenerative medicine product, then bring in more hospitals. That would still be a beginning, not an end. But for someone facing a 15-year wait and a lifetime tethered to a dialysis machine, even a bridge is far more than what exists today.

So here is the question worth sitting with. In Japan, deep donor shortages and long-held attitudes toward donation have pushed researchers toward pigs. How does organ donation work where you live, and if it came to it, would you accept a kidney grown in an animal?

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