Archive · 4 Sep 2026
Gene-Edited Pig Kidney Bridges Patient to Human Transplant
Tim Andrews had severe kidney disease and needed dialysis to stay alive.
Doctors gave him a kidney from a specially gene-edited pig.
The kidney started working right away.
It kept him off dialysis for 271 days, or about nine months.
This gave him time to wait for a human kidney.
The pig kidney later became inflamed and its small blood vessels were damaged.
Doctors removed it, and Andrews used dialysis again for 82 days.
He then received a kidney from a deceased human donor.
Doctors found no pig-virus transmission or immune changes that stopped the human transplant from working.
Tim Andrews, 66, lived 271 days without dialysis using a genetically modified pig kidney.
The organ came from Wilma, a Yucatan miniature pig whose genome was altered 69 times.
The kidney began working immediately and allowed Andrews to resume daily activities for nine months.
Blood-vessel damage, inflammation and declining function led doctors to remove the pig kidney after 271 days.
After 82 days back on dialysis, Andrews received a deceased-donor human kidney that was functioning normally during follow-up.
- Who
- Tim Andrews, a 66-year-old man from New Hampshire, received the pig kidney and later a deceased-donor human kidney.
- What
- A genetically modified pig kidney supported Andrews without dialysis before he received a human kidney transplant.
- When
- The pig-kidney transplant occurred on January 25, 2025; the pig kidney was removed in October 2025, and the human transplant took place in January 2026.
- Where
- The procedures took place in the United States, involving Massachusetts General Hospital and Mass General Brigham.
- Why
- Doctors used the pig kidney as a temporary bridge while Andrews waited for a suitable human donor organ.
Potential Benefits
Remaining Concerns
Temporary bridge to transplantation
Potential Benefits
Researchers say a gene-edited pig kidney could keep patients off dialysis while they wait for a human donor.
Remaining Concerns
The case involved one patient and does not establish that pig kidneys are ready for routine use as a bridge.
Long-term function
Potential Benefits
The kidney functioned for 271 days, the longest reported dialysis-free survival after a pig-kidney transplant in a living human.
Remaining Concerns
The organ later developed microvascular damage, inflammation and declining function, showing that durability remains a challenge.
Safety and future use
Potential Benefits
No pig pathogens or complicating antibodies were detected, and Andrews successfully received a human kidney afterward.
Remaining Concerns
Researchers say larger studies are still needed to assess durability, zoonotic infection risk, immunosuppression and possible immune sensitization; animal-support groups also raise ethical objections.
- Patient
- Tim Andrews, 66, from New Hampshire
- Dialysis-free period
- 271 days
- Pig donor
- Wilma, a genetically modified Yucatan miniature pig
- Genetic edits
- 69 alterations intended to improve human compatibility and reduce rejection and viral risks
- Pig-kidney outcome
- Blood-vessel damage, inflammation and declining function led to removal after nine months
- Human transplant
- A deceased-donor kidney was implanted in January 2026 after 82 days of dialysis
- Safety findings
- Doctors reported no pig-virus or other pathogen transmission and no antibodies that complicated the human transplant
- Publication
- The Lancet
Sources
Man Spends 9 Months With Pig Kidney, Later Receives Human Organ In World-First Medical Milestone
Pig kidney keeps patient off dialysis for 271 days before human transplant
Man Lives Record 271 Days Without Dialysis Using Gene-Edited Pig Kidney, Then Gets Human Transplant