TOKYO - PorMedTec, a Meiji University startup, has begun producing genetically modified pigs for a clinical trial that could start in Japan in 2028 and transplant pig kidneys into patients with kidney failure.
The Kawasaki-based company and Shonan Kamakura General Hospital in Kamakura, Kanagawa Prefecture, announced the start of production at a news conference on July 21. PorMedTec plans to submit a clinical trial notification in fiscal 2027 and conduct the study at Shonan Kamakura General Hospital and Hokkaido University Hospital.
The experimental treatment, known as xenotransplantation, is being developed as a possible third option for patients with severe kidney failure, alongside dialysis and transplantation of a human kidney.
Producing each donor pig takes about 18 months, including cloning, birth and growth to a suitable size. PorMedTec said it has started production now to ensure that donor animals are available when the planned trial begins.
The company will use the same type of genetically modified pigs as those involved in clinical studies at Massachusetts General Hospital, affiliated with Harvard University, in the United States. Four patients had received kidneys from pigs of the same clone as of July 2026.
The first transplant was conducted in January 2025. The patient remained off dialysis for 38 weeks, or about nine months, before temporarily resuming treatment and receiving a kidney from a deceased human donor in January 2026.
The second patient, who received a pig kidney in June 2025, remained free of dialysis for 34 weeks, or about eight months. After temporarily returning to dialysis, the patient received a human kidney in June 2026.
A third patient underwent surgery in November 2025 and had returned to ordinary life without dialysis as of July 21. A fourth transplant was performed in June 2026.
The first three cases exceeded the U.S. Food and Drug Administration's effectiveness benchmark of at least 24 weeks without dialysis. Further studies are planned at Massachusetts General Hospital before the trial expands to eight medical institutions across the United States. The U.S. program is expected to conclude during 2028.
PorMedTec plans to use the American data when seeking permission for a smaller supplementary trial in Japan. The company said the scale of the Japanese study has not yet been agreed with the Pharmaceuticals and Medical Devices Agency.
The pig kidneys are expected to be classified in Japan as regenerative medical products. PorMedTec plans to seek conditional marketing approval based on the trial results before expanding clinical use to other hospitals.
The donor pigs were originally developed by U.S. biotechnology company eGenesis. Three pig genes associated with immediate immune rejection have been disabled, while seven human genes have been inserted to help regulate immune responses, blood clotting and macrophage activity.
The animals have also had 59 copies of porcine endogenous retrovirus genes disabled. These viral sequences occur naturally in the pig genome but have long raised concerns that they could become active after transplantation into a heavily immunosuppressed patient.
The seven human genes are inserted together into one location in the pig genome using genome-editing technology. The edited cell nucleus is then transferred into a pig egg from which the original nucleus has been removed, producing a cloned embryo without conventional fertilization.
The embryo is implanted into an unmodified surrogate sow. After a pregnancy of about four months, the piglets are delivered by cesarean section to prevent infection during birth.
They are then raised in highly controlled designated pathogen-free conditions, first in sealed artificial-rearing equipment and later in clean rooms comparable to those used in regenerative medicine. The pigs are generally raised for seven to 12 months before becoming organ donors.
Doctors at Shonan Kamakura General Hospital conducted their first practice kidney-removal procedure using one of the genetically modified pigs on July 21 at a Meiji University-related facility. Hokkaido University doctors conducted a similar exercise in April.
Additional practice sessions will be held using pigs from the same clone and of approximately the same size as those intended for the trial. Doctors will also rehearse cooling, preserving and transporting the kidneys from the removal facility to the hospital.
The pig used in the latest exercise weighed about 70 kilograms. Its kidney weighed around 180 grams, approximately the same size as a human kidney, which weighs about 180 grams in an adult man and 150 grams in an adult woman.
The surgical team said the pig kidney's blood vessels were clean and similar to human vessels, while the ureter was sufficiently long for transplantation. The procedure to remove the organ took about one hour.
Facilities for removing kidneys will be built near both Shonan Kamakura General Hospital and Hokkaido University Hospital by the end of 2027. On the day of a transplant, a donor pig would be transported from its breeding facility to the nearby removal center, allowing the kidney to be transferred rapidly to the recipient.
Medical teams said rejection, damage to blood vessel linings, abnormal blood clotting and infection will remain major challenges. Patients are also expected to require stronger immunosuppressive treatment than recipients of human organs.
The criteria for participating in the Japanese study have not been finalized. In the U.S. cases, recipients were generally in their 50s or 60s, had been receiving dialysis for at least two years and did not have serious heart disease or other major complications.
Doctors said inquiries had already been received from patients seeking access to the treatment. Some patients had been undergoing dialysis for about 10 years and wanted even a short period of life without its restrictions.
Japan has one of the world's lowest rates of organ donation, with 1.13 donors per million people, compared with 49.7 per million in the United States, according to figures presented at the news conference.
About 350,000 people in Japan receive dialysis, while only around 200 kidney transplants from deceased donors are conducted annually. Patients who receive a deceased-donor kidney wait an average of about 15 years, and some become too ill to remain on the waiting list.
PorMedTec said pig-kidney transplantation could serve either as a long-term treatment or as a bridge until a human organ becomes available. The goal is to make the procedure one of Japan's standard treatment options by 2033.
The company currently estimates that its cloning team could produce about 100 pigs a year. It eventually plans to create genetically modified male and female breeding animals, allowing conventional reproduction to raise annual production into the thousands or potentially tens of thousands.
A survey conducted among dialysis patients and their families at a symposium in February found that 62% would consider receiving a pig kidney if recommended by their doctor. Of those respondents, 72% said they would travel overseas for the procedure if it were unavailable in Japan.
Hospital officials acknowledged that xenotransplantation raises ethical and animal-welfare concerns and said the technology would require careful public discussion. They said, however, that the severe shortage of human donor kidneys made it important to develop another treatment capable of reducing patients' dependence on dialysis.
Source: Kyodo
