Japan faces one of the most severe organ donor shortages among developed nations. According to the Japan Organ Transplant Network, approximately 16,000 people are currently waiting for organ transplants, yet only about 4% receive the organs they need each year. In the Japan Society for Transplantation's international comparison of deceased donors per million population, Spain leads with 46.03 and the United States follows at 44.50, while Japan registers 0.88.

The kidney transplant waiting list is particularly critical, with over 14,000 patients awaiting a transplant. The average waiting period extends to approximately 15 years, during which many patients continue dialysis treatment while their health deteriorates. Tragically, an estimated eight patients die each week while waiting for a transplant that never comes.

A University Startup Takes on Xenotransplantation

Amid this challenging landscape, a technology called "xenotransplantation," the transplantation of organs from animals such as pigs into humans, has emerged as a possible way through. Pormedtec, a startup spun out of Meiji University based in Kawasaki City, is targeting Japan's first clinical trials of pig-to-human organ transplantation by fiscal year 2027.

The company has partnered with US biotechnology firm eGenesis, which provides genetically modified pig cells engineered to reduce human immune rejection. Pormedtec produces clone pigs domestically using these cells, establishing a complete production pipeline in Japan.

In February 2024, three pigs specifically bred for xenotransplantation were born in Japan for the first time. These animals carry 10 genetic modifications designed to minimize immune rejection responses. The company plans to open a specialized breeding facility in Osaka Prefecture in late 2027, implementing automated feeding and cleaning systems along with sensor-based health monitoring to minimize human-pig contact and reduce infection risks.

[Update, July 31, 2026] On June 29, 2026, Pormedtec announced a basic agreement with Hokkaido University and the Tokushukai group to run the trial at Hokkaido University Hospital in Sapporo and Shonan Kamakura General Hospital in Kanagawa, with a start now targeted for 2028 rather than fiscal 2027. The company plans to file its protocol with Japan's Pharmaceuticals and Medical Devices Agency around 2027 and to enroll a handful of patients, mainly people in their sixties on dialysis for chronic kidney failure. A new breeding site in Kyoto Prefecture is meant to lift output from 50 pigs a year to roughly 100.

What US Clinical Research Has Shown

Clinical research in the United States has moved quickly. eGenesis carried out four pig kidney transplants between March 2024 and November 2025, and the longest a patient went without dialysis was 271 days, according to figures Pormedtec published in June 2026. Two of those cases reached 24 weeks off dialysis. What is being measured here is time free of dialysis rather than patient survival: it is an indicator of how long the transplanted organ kept working inside the body.

Other companies are also advancing toward clinical applications. United Therapeutics received regulatory approval for kidney transplant clinical trials, and multiple organizations are actively pursuing human trials. In March 2024, Massachusetts General Hospital performed the world's first pig kidney transplant into a living patient.

Technological Advances and Remaining Challenges

The feasibility of xenotransplantation has improved sharply thanks to advances in genome editing. Pig cells naturally express carbohydrate antigens on their surface that the human immune system recognizes as foreign, previously triggering hyperacute rejection that destroyed transplanted organs within minutes.

Modern genome editing tools like CRISPR-Cas9 now enable researchers to knock out genes responsible for these rejection-triggering antigens while introducing human genes that help evade immune detection. Scientists have created pigs with up to 69 genomic edits, achieving survival periods of up to 758 days in cynomolgus monkey transplant recipients.

However, significant challenges remain. The risk of porcine endogenous retroviruses (PERVs) potentially infecting human recipients continues to concern researchers, necessitating stringent health management of donor pigs. Long-term immune responses and interactions between pig-derived factors and human physiology also require further investigation.

Prospects and Social Considerations in Japan

Professor Hiroshi Nagashima of Meiji University, founder of Pormedtec, emphasizes that "Japan has fewer donors than other developed countries. The need for xenotransplantation may actually be higher here than in the US, where trials are progressing." The company's clinical trial goal is to achieve six months of dialysis-free survival post-transplant. If successful, this could enable various clinical applications, from lifetime organ use to bridging patients until human donor organs become available.

Beyond technical challenges, gaining social acceptance remains crucial for xenotransplantation's implementation. Psychological resistance to receiving animal organs and ethical concerns about using animals for human benefit require careful dialogue through patient and public symposiums.

Additionally, a team from Jikei University School of Medicine and the National Center for Child Health and Development is planning clinical research to transplant pig kidneys into fetuses with Potter syndrome, a condition where kidneys fail to form properly, representing a uniquely Japanese approach to the technology.

Policy has moved too. On June 24, 2026, the Japan Growth Strategy Council included xenogeneic kidney transplantation in a draft public-private investment roadmap covering 17 strategic fields. Trial preparations draw on an AMED innovation programme and a METI subsidy for manufacturing facilities. There has also been public dialogue: on February 15, 2026, Meiji University and Pormedtec held an open symposium attended by 120 people, including clinicians, kidney failure patients and their families. Speakers included the surgeon who performed the transplants at Massachusetts General Hospital, doctors from the two hospitals slated to run the trial, and a bioethics researcher (as of September 2026).

Ethical debates about using animal organs, and concerns about unknown risks, are far from settled. What is the transplantation situation in your country, and what do people there say about taking an organ from an animal?

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