Archive · 5 Sep 2026
Genetically Modified Pig Kidney Bridges Man to Human Transplant
Tim Andrews had very serious kidney disease caused by type 2 diabetes.
He was unlikely to receive a human kidney soon.
In January 2025, doctors gave him a kidney from a specially modified pig named Wilma.
The pig kidney worked for 271 days, or about nine months.
This allowed Andrews to live without dialysis during that time.
Doctors later removed the pig kidney after it began to fail.
Andrews used dialysis for 82 days and then received a kidney from a deceased human donor.
The human kidney worked well during six months of follow-up, and doctors found no pig viruses or other pathogens.
A genetically modified pig kidney functioned in 66-year-old Tim Andrews for 271 days.
The transplant kept Andrews off dialysis for about nine months, the longest recorded period in a living human.
Andrews had only a 9% chance of receiving a human kidney within five years because of kidney failure caused by type 2 diabetes.
After the pig kidney was removed in October 2025, Andrews underwent 82 days of dialysis before receiving a deceased-donor human kidney.
The human kidney functioned well during six months of follow-up, with no pig viruses or other pathogens detected.
- Who
- Tim Andrews, a 66-year-old US man with end-stage kidney disease, and physicians at Massachusetts General Hospital.
- What
- A genetically modified pig kidney functioned for 271 days as a temporary bridge before Andrews received a human donor kidney.
- When
- The pig-kidney transplant occurred in January 2025; it was removed in October 2025, followed by a human transplant after 82 days of dialysis.
- Where
- Massachusetts General Hospital in Boston, United States.
- Why
- Andrews had only a 9% chance of receiving a human kidney within five years, while his risk of dying or being removed from the waiting list exceeded 40%.
Potential Benefits
Scientific Cautions
Reducing the organ shortage
Potential Benefits
Researchers said pig kidneys could initially serve as a bridge, helping patients stay off dialysis while they wait for a human donor.
Scientific Cautions
The researchers emphasized that this was a single-patient case with no comparison group, so further clinical trials are needed.
Long-term treatment
Potential Benefits
Dr Leonardo Riella said xenotransplantation could eventually become a permanent treatment if its safety and durability are established.
Scientific Cautions
The transplanted pig kidney eventually failed after damage developed in its blood vessels, showing that its long-term durability remains uncertain.
Safety for later transplantation
Potential Benefits
The later human kidney functioned well, with no new antibodies against human tissue and no detected pig viruses or other pathogens.
Scientific Cautions
The absence of detected pathogens and antibodies in this case does not establish safety for all future patients; broader testing and trials are still required.
- Patient
- Tim Andrews, age 66
- Underlying condition
- End-stage kidney disease caused by type 2 diabetes
- Pig kidney duration
- 271 days, or approximately nine months
- Genetic modifications
- The pig genome underwent 69 edits
- Dialysis after removal
- 82 days
- Human kidney follow-up
- The deceased-donor kidney functioned well after six months
- Pathogen findings
- No pig viruses or other pig pathogens were detected
