Man Lives for Nine Months With Genetically Modified Pig Kidney in Medical First

A major breakthrough in transplant medicine has been reported after a 66-year-old man lived for nine months with a genetically modified pig kidney, marking an important step forward in the development of animal-to-human organ transplantation.

Tim Andrews, from New Hampshire in the United States, had end-stage kidney disease before undergoing the experimental procedure in January 2025. Instead of remaining dependent on dialysis while waiting for a suitable human donor, he received a kidney taken from a genetically engineered Yucatan miniature pig.

The experimental organ functioned for 271 days, allowing Andrews to live without dialysis for approximately nine months. He was eventually able to receive a kidney from a deceased human donor, making the pig kidney a temporary bridge rather than a permanent replacement.

The development could have significant implications for people with advanced kidney disease who spend long periods waiting for a human organ.

A New Approach to the Organ Shortage

Kidney failure affects millions of people worldwide, and transplantation is generally considered one of the best treatment options for patients with end-stage kidney disease. However, the number of people who need organs continues to exceed the number of kidneys available for transplantation.

This shortage means that some patients remain on dialysis for extended periods while waiting for a suitable donor. For some, the wait can have serious consequences for their health and quality of life.

Doctors involved in Andrews' treatment believe genetically modified pig organs could eventually help address this problem.

The concept is known as xenotransplantation, which refers to transplanting organs or tissues from one species into another. In this case, researchers are attempting to make pig organs more compatible with the human body by changing specific genes.

The kidney used in Andrews' procedure was genetically engineered to reduce the likelihood that his immune system would immediately identify the organ as foreign and attack it.

Why Are Pigs Being Used?

Pigs have become a major focus of xenotransplantation research because their organs are considered relatively similar to human organs in terms of size and anatomy.

However, simply transplanting an ordinary pig kidney into a human would not be expected to work safely for an extended period. The human immune system can recognise animal tissue as foreign, potentially triggering severe rejection.

Advances in genetic engineering have given researchers new ways to modify pig organs before transplantation.

According to experts quoted in the source article, researchers can remove or alter certain pig genes so the human immune system is less likely to recognise the transplanted organ as incompatible.

Technologies such as CRISPR gene editing have contributed to this progress by allowing scientists to make highly targeted changes to DNA.

The goal is not simply to make an animal organ survive inside a human body for a short period. Researchers ultimately want to determine whether modified organs can provide reliable and safe kidney function for much longer periods.

The Pig Kidney Worked for 271 Days

The kidney transplanted into Andrews began functioning immediately after the procedure.

For roughly six months, the organ continued to work before doctors identified damage affecting its blood vessels. The condition eventually progressed to organ failure, and the pig kidney was removed.

Andrews then spent a short period on dialysis before receiving a kidney from a deceased human donor.

Although the experimental kidney did not function permanently, its ability to support him for 271 days is considered an important milestone. Medical teams described the case as the longest recorded dialysis-free survival following a pig kidney transplant in a living patient.

It was also described as the first successful transition from a pig kidney transplant to a human donor kidney.

For researchers, the result demonstrates the possibility of using an animal organ as a temporary solution while a patient waits for a human transplant.

What Was Life Like After the Transplant?

For Andrews, the procedure was not simply a scientific experiment. It gave him an opportunity to spend months living without dialysis.

He later described the experience as a miracle. He also said he was able to return to ordinary activities, including cooking, vacuuming and taking long walks with his dog, Cupcake.

These everyday activities highlight one of the potential benefits of successful xenotransplantation.

Dialysis can be time-consuming and physically demanding. Patients often need regular treatment to perform functions that healthy kidneys normally carry out, including removing waste and excess fluid from the blood.

If a transplanted animal kidney could safely perform those functions, it could potentially give patients greater freedom while they wait for a human organ.

Researchers Found No Pig Viruses

Safety remains one of the biggest concerns surrounding xenotransplantation.

Animal organs can potentially carry infectious agents that could pose risks to human recipients. For that reason, researchers closely monitored Andrews during and after the procedure.

According to the research team, no pig viruses or other pig pathogens were detected during the period of the transplant.

This finding is encouraging, but it does not mean that all risks associated with xenotransplantation have been eliminated.

The procedure remains experimental, and researchers need more evidence before genetically modified animal organs can become a routine treatment.

What Does This Mean for the Future?

Dr Leonardo Riella, lead author of the research from Mass General Brigham, said the shortage of human organs remains one of the biggest challenges in transplantation.

The researchers see xenotransplantation potentially developing in stages.

Initially, genetically modified pig organs could be used as a bridge for patients who need kidney function while waiting for a human donor. In the longer term, researchers hope that improvements in safety and durability could make animal organs suitable as a more permanent treatment.

That future, however, is still uncertain.

Another pig kidney transplant performed at Massachusetts General Hospital in 2024 involved a living human recipient who survived for 52 days before dying from heart-related problems that were reported as unrelated to the transplant.

These cases show both the promise and the limitations of the technology.

Is Pig Kidney Transplantation Available in the UK?

At present, there are no clinical trials for this type of procedure in the UK, according to the source article.

UK regulators and health authorities have nevertheless been considering how animal-to-human transplantation could potentially be regulated.

Experts have also highlighted ethical issues, including animal welfare, safety, regulation and long-term monitoring.

Public attitudes may also influence the future development of the technology. Research cited by UK experts suggests that many people are supportive of animal-to-human transplantation when it is demonstrated to be safe and effective.

However, experts stress that there is still a considerable distance between experimental procedures and widespread medical use.

A Potential New Chapter in Transplant Medicine

Tim Andrews' experience represents an important development in the search for alternatives to human donor organs.

His genetically modified pig kidney did not provide lifelong kidney function, but it worked long enough to keep him free from dialysis for 271 days before he moved on to a human donor kidney.

For researchers, that result offers evidence that xenotransplantation could potentially serve as a bridge for patients facing long waits for human organs.

Much more research will be needed to determine how long genetically modified animal kidneys can function, how safely they can be used, and whether the approach can eventually become a standard treatment.

For now, the case provides a glimpse of a possible future in which patients with kidney failure may have another option while waiting for a human transplant.

As genetic engineering continues to develop, animal organs could potentially become part of efforts to address the global shortage of transplantable organs.

Source

The Independent on 4 September 2026.

Disclaimer

This article is provided for general informational and educational purposes only. Xenotransplantation remains an emerging area of medical research, and experimental findings should not be interpreted as evidence that pig kidney transplantation is currently an established or routinely available treatment. Anyone seeking medical advice about kidney disease, dialysis or transplantation should consult a qualified healthcare professional.