Full Breakdown
Pig Kidney Transplant Gives Patient Nine-Month Dialysis-Free Bridge to Human Organ
9/4/2026, 4:01:36 AM
Core Event
In late January 2025, 66-year-old Tim Andrews of New Hampshire received a genetically edited kidney from a Yucatan miniature pig named Wilma at Mass General Brigham. The organ was engineered to reduce immune rejection and to eliminate pig viruses. Andrews lived without dialysis for 271 days—the longest recorded period for a pig-to-human kidney xenograft—before the kidney failed and was removed. After a short return to dialysis, he received a deceased-donor human kidney in early 2026.
Background & Context
End-stage kidney disease affects millions, and demand for donor kidneys far exceeds supply. In the United States roughly 100,000 people await a kidney each year while only about 25,000 transplants occur annually. Prior xenotransplant attempts include a 2024 pig-kidney transplant that lasted 52 days before the recipient died of unrelated heart problems, and a 2022 pig-heart transplant that ended months later, possibly due to a pig virus. These earlier cases had not demonstrated survival beyond two months.
Data & Statistics
- Andrews entered the study with a 9 % estimated chance of receiving a human kidney within five years, versus a >40 % risk of death or removal from the waiting list.
- The pig kidney functioned for 271 days (nine months), the longest documented xenograft survival in a living patient.
- No new antibodies against human tissue or pig pathogens were detected during the bridge period.
- The United States has about 600,000 people on dialysis, costing roughly $100,000 per patient per year.
Official Statements & Responses
Mass General Brigham’s transplant team reported that the pig kidney acted as a “bridge” to a human transplant, allowing Andrews to resume normal activities such as cooking and walking his dog. They emphasized that the outcome reflects careful patient selection and intensive specialist care that may not be universally available. The team also noted that the procedure was experimental, with five similar transplants performed to date and additional case reports forthcoming. Researchers highlighted the need for further trials to establish long-term safety and durability before broader clinical use.
Why It Matters
The successful bridge demonstrates that xenotransplantation can extend dialysis-free survival for patients facing long waiting times, potentially reducing the physical wear of dialysis and associated healthcare costs. If future studies confirm safety and durability, pig kidneys could evolve from a temporary bridge to a permanent therapeutic option, alleviating the organ shortage crisis.
Verbatim Quotes
- “The organ shortage is the greatest crisis we have right now in transplantation,” — Dr Leonardo Riella, lead author
- “The patients are the true pioneers here,” — Leonardo Riella, lead author
- “I think it’s incredible in terms of the science behind it and what they’ve achieved,” — Michelle Willicombe, at Imperial College London
- “Such transplants may allow patients to avoid going through dialysis, which is so important because it causes so much wear and tear to the body,” — Leonardo Riella, lead author
What's Next
The research team plans to publish two additional case reports this year, including one that has already surpassed Andrews’s nine-month record. Ongoing trials will assess whether genetically modified pig kidneys can become a routine bridge—or eventually a destination—therapy for end-stage kidney disease.
