Japan Moves Toward First Pig-to-Human Organ Transplant Clinical Trials—Could Xenotransplantation Solve the Donor Crisis?
Japan's Critical Organ Shortage
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. When comparing organ donor rates per million population internationally, Spain leads with 46.03 donors, followed by the United States at 44.50, while Japan registers a mere 0.88—a stark contrast that highlights the severity of the issue.
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 potential game-changer. 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.
Breakthrough Results from US Clinical Research
Clinical research in the United States has achieved remarkable progress. In September 2024, eGenesis announced that a patient who received a genetically modified pig kidney has survived more than seven months—setting a new world record for xenotransplant organ survival. This demonstrates that transplanted pig organs can function long-term in the human 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, marking a historic milestone.
Technological Advances and Remaining Challenges
The feasibility of xenotransplantation has dramatically improved due to revolutionary advances in genome editing technology. 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.
What Does Organ Transplantation Look Like in Your Country?
In Japan, the severe donor shortage has intensified expectations for xenotransplantation as a new option. For patients enduring years of dialysis while waiting for transplants, and for their families, these technological advances represent profound hope.
At the same time, ethical debates about using animal organs and concerns about unknown risks persist. What is the organ transplantation situation in your country? What opinions exist about animal-to-human organ transplants? We would love to hear your thoughts and perspectives on this groundbreaking medical frontier.
References
- https://newswitch.jp/p/47896
- https://www.jotnw.or.jp/explanation/07/06/
- https://www.asas.or.jp/jst/general/number/
- https://natgeo.nikkeibp.co.jp/atcl/news/25/052000267/
- https://www.nikkei.com/article/DGXZQOUC088N00Y4A200C2000000/
- https://www.igaku-shoin.co.jp/paper/archive/y2025/3572_08
- https://www.natureasia.com/ja-jp/nature/pr-highlights/14683
Reactions in Japan
As someone who has treated dialysis patients for many years, I've been waiting for xenotransplantation to advance. Knowing the suffering of patients who endure over 4 hours of dialysis three times a week for years, I can't help but have high hopes for this technology.
My father has been waiting for a kidney transplant for over 15 years. Honestly, I felt resistance when I first heard about pig organs, but if it could save his life... Having more options gives us hope.
The technological progress is impressive, but the ethical issues of treating animals as organ factories need careful discussion. I question the notion that anything is permissible for human life.
Meiji University's technology is amazing. Having internationally top-class success rates in somatic cell cloning may seem unglamorous, but it's truly remarkable. Japanese technology could change global medicine.
Is the infection risk really okay? After learning how scary animal-derived viruses can be from COVID, I'm a bit worried about what might happen if pig viruses infect humans...
I witness the suffering of patients and families waiting for transplants every day. If xenotransplantation becomes reality, we might reduce deaths during the waiting period. Safety confirmation is essential, but I hope we move forward.
From a Buddhist perspective, all life is equally precious. There's conflict about sacrificing pigs for humans. However, the desire to save suffering people is equally important.
Pormedtec's moves are noteworthy. This is a deep tech field where Japan can compete globally. However, the path to commercialization is long, so investment decisions should be careful.
Working in a dialysis ward, I often hear patients say 'I wish I could get a transplant.' Japan really has few donors. If xenotransplantation becomes an option, more people will definitely be saved.
Pigs born only to be killed for organ transplants. Is this ethically acceptable? Shouldn't we first do more to increase organ donation registrations?
Seven months of survival in the US is groundbreaking. However, the 6-month dialysis-free goal still presents challenges compared to same-species transplants. Still, it has sufficient value as a bridge treatment.
We live in an era where gene editing technology is being utilized in medicine to this extent. I can introduce this as a real-world example when teaching students. I want them to think about both technological progress and ethics.
Japan's low organ donation rate is partly a systemic issue. Countries with opt-out systems tend to have higher donation rates. Alongside xenotransplantation, we need to discuss institutional reforms.
The combination with immunosuppressants will likely be key. Development of immunosuppression protocols specific to xenotransplantation is also progressing. This is a field requiring a comprehensive approach.
Patient opinions on xenotransplantation vary. Some have hope, others feel anxious about unknown risks. When given choices, it's important to create an environment where people can make informed decisions.
As someone who raises pigs, I have mixed feelings. Apparently the breeding environment for food and medical use is completely different, but both involve facing life and death.
As someone aiming to become a transplant surgeon, the development of xenotransplantation is very interesting. If clinical trials actually begin in Japan, it will attract worldwide attention.
While reporting on technological progress, we need to accurately cover the challenges too. I want to provide coverage that maintains hope without creating excessive expectations.
As a nephrologist in the US, I have high hopes for xenotransplantation advances. My clinic has many patients who have been waiting for transplants for years. It's wonderful news that Japanese research teams are moving toward clinical trials. International cooperation will advance this field.
Spain leads the world in organ donation rates, but we still can't meet demand. Japan's xenotransplantation research could give hope to patients worldwide. Even with high technical hurdles, I think it's worth the challenge.
As a German bioethicist, I believe this technology requires a cautious approach. How to balance animal rights with human medical needs is an important issue that society must discuss. Japan's emphasis on public dialogue is commendable.
Xenotransplantation research is drawing attention in the UK as well. The success cases from eGenesis particularly shocked the entire medical community. Japan's technical capabilities and strict safety standards could make important contributions to this field.
In the Middle East, some regions have religious resistance to organ transplants. However, from the perspective of saving lives, many Islamic scholars accept it as a necessary medical procedure. Opinions are divided regarding pig organs specifically.
Organ shortage is a serious problem in China too. The efforts by the Meiji University startup could impact transplant medicine across Asia. I hope technical knowledge sharing will advance.
Korea suffers from donor shortages similar to Japan. If xenotransplantation becomes practical, it would be a great hope for patients in both countries. I hope Japan-Korea research cooperation will advance.
Brazil has many dialysis patients, and many are waiting for transplants. I hope technologies developed in advanced countries will eventually benefit developing nations too. Cost remains a major challenge though.
I'm a transplant surgeon in Australia. The 7+ month survival record shows technology is definitely advancing. However, long-term safety data is still insufficient. I hope for careful but steady progress.
France has an opt-out system for organ donation, so our rates are relatively high. Still, we welcome xenotransplantation development. As a complementary option, it can give new hope to patients.
As a Canadian animal welfare organization, we have mixed feelings about this technology. We understand its potential to save lives, but animal welfare must also be considered. I hope Japanese researchers won't forget ethical considerations.
Organ trafficking is a serious problem in India. If xenotransplantation can be safely implemented, it might help reduce unethical organ trade. This technology is meaningful for developing countries too.
I'm a medical student in Poland. The fusion of genome editing and transplant medicine is truly the frontier of 21st-century medicine. I dream of researching in this field someday. I'm following Japanese research outcomes closely.
Social awareness of organ donation is growing in Ireland, but we still can't meet demand. Japan's efforts are like a lighthouse for transplant waiting patients around the world.
From a Swedish public health perspective, managing infection risk is the top priority. Japan's strict hygiene management system is instructive. I hope Japanese expertise will be utilized in developing international guidelines.
Due to New Zealand's small population, organ transplant opportunities are limited. If xenotransplantation becomes practical, patients in rural areas and small countries might receive equal access to treatment.