Gene-Edited Pig Kidney Kept US Man Off Dialysis for 9 Months Before He Received a Human Kidney

September 4, 2026: In a study published by The Lancet on September 3, 2026, a genetically modified pig kidney worked without dialysis for 271 days before doctors replaced it with a kidney from a human donor. The researchers said that this case provided the first documented example of a pig kidney serving as a temporary bridge to a human transplant. 

Tim Andrews had end-stage kidney disease linked to type 2 diabetes. He had been receiving hemodialysis for about 2 years. In the absence of a suitable living kidney donor, he was waiting for a kidney from a deceased donor. His chances of receiving a transplant within five years were estimated at about 9%. However, his chances of dying or being removed from the waiting list were estimated at more than 40%. He had also been told that the wait for a human kidney could extend to up to 7 years.

Under an FDA Expanded Access Investigational New Drug application, Andrews received the experimental pig kidney at Massachusetts General Hospital in Boston on January 25, 2025. At the time, he was the fourth person to receive a genetically edited pig kidney in the world.

The organ came from a genetically modified Yucatan miniature pig named Wilma. Researchers made 69 genomic modifications to the pig's genome to reduce the risk of immune rejection and infection and make the kidney more compatible with the human body. The modifications included changes intended to remove pig molecules recognised by the human immune system, add human genes that help regulate immune responses and inactivate pig endogenous retroviruses carried within the pig genome.

How Long Did the Pig Kidney Work? 271 Days Without Dialysis

The kidney began functioning immediately after transplantation. Andrews started to experience early signs of T-cell-mediated rejection. But the doctors controlled the response by adjusting his immunosuppressive treatment. He remained free from dialysis while the pig kidney was functioning.

After six months since transplantation, the kidneys started to develop damage to its small blood vessels and become inflamed. The researchers identified thrombotic microangiopathy, a condition involving injury and clot formation in small blood vessels, as part of the progressive damage. The exact cause of the kidney’s failure remained unclear. The doctors were not able to detect any antibodies attacking the pig kidney.

The treatment for immunosuppression had been reduced after 6 months due to an infection developed in Andrews. The doctors removed the pig kidney in October 2025 after it functioned for 271 days. Later, Andrews returned to dialysis for 82 days. 

During the period he had the pig kidney, researchers had found no evidence of transmission of pig-derived pathogens. They also monitored his immune response and kidney function.

What Happened After the Pig Kidney Was Removed?

Andrews received a kidney from a deceased human donor in January 2026. Following the transplant, the human kidney continued to function well. The doctors found no new antibodies against human tissue that would have made the subsequent transplant even more difficult.

He was able to receive the human kidney earlier than expected because it had the highest possible level of tissue compatibility. Researchers noted that such a high level of compatibility is uncommon and difficult to predict.

How Gene-Edited Pig Kidney Transplants Have Progressed

Before genetically modified pig kidneys were transplanted into living patients, researchers first studied how the organs functioned and how the human immune system responded to them in deceased human recipients. The University of Alabama at Birmingham connected a genetically modified pig kidney to a brain-dead human recipient in 2021. 

These experiments demonstrated that genetically modified pig kidneys can function in the human body without being rejected right away.

The first genetically modified pig kidney transplant was performed on a living human at Massachusetts General Hospital in March 2024. After suffering from end-stage kidney disease Richard "Rick" Slayman received the kidney. He passed away 52 days after the procedure due to cardiac issues that doctors said were unrelated to the transplant.

In April 2024, Lisa Pisano received a gene-edited pig kidney along with a mechanical heart pump at NYU Langone Health. Later, Towana Looney received a gene-edited pig kidney after dealing with dialysis for a long time in November 2024. 

What Comes Next for Gene-Edited Pig Kidney Transplants?

The US Food and Drug Administration has since cleared clinical trials of eGenesis’ gene-edited pig kidney, EGEN-2784. According to the company, five patients had received the kidney through expanded access since March 2024. 

As of September 3, 2026, three of the patients had been able to maintain kidney function for more than eight months without dialysis. eGenesis plans to test EGEN-2784 in the Phase 1/2/3 RESTORE trial, which is expected to start in 2027 and include 33 people with kidney failure.

At 271 days, Andrews had the longest reported period of support from a pig kidney before receiving a human kidney when the Lancet report was published. However, that is no longer the overall record. By September 3, 2026, another woman had reportedly reached 285 days with a gene-edited pig kidney.

(Rh/MSM)