Man Lives 9 Months with Pig Kidney Before Human Transplant

The Patient Journey and the Organ Shortage Crisis

The study participant, Tim Andrews, lived with end-stage kidney disease caused by type 2 diabetes and had spent two years on haemodialysis before receiving the xenotransplant on January 25, 2025, according to Mass General Brigham. Andrews lacked a living donor and faced an expected wait time of over five years on the deceased-donor list. According to the Kidney Transplant Decision Tool, his probability of receiving a timely transplant sat at roughly 9%, while his risk of death or removal from the waiting list exceeded 40%, as reported by the study authors. “The organ shortage is the greatest crisis we have right now in transplantation,” said Dr. Leonardo Riella, medical director of kidney transplantation at Mass General Brigham, noting that dialysis imposes a heavy physical and emotional toll.

Genomic Modifications and Surgical Outcome

To make the cross-species transplant viable, surgeons implanted a kidney from a Yucatan miniature pig named Wilma that featured 69 genomic edits designed to control size, improve immune compatibility, and reduce the risk of human-targeting viruses, according to The Lancet report. The organ started working immediately, lifting Andrews out of what he called “dialysis foggy” exhaustion and giving him renewed energy to walk his dog, Cupcake, and handle household chores. However, after roughly six months, blood vessel damage developed in the pig kidney, eventually leading to organ failure after 271 days. Surgeons removed the organ in October, and Andrews temporarily returned to dialysis.

Transitioning to a Human Kidney Transplant

Following the removal of the pig kidney, medical teams at Mass General Brigham tested Andrews for new antibodies that could complicate a subsequent human organ transplant and found none, according to hospital disclosures. On January 12, the hospital notified him that a deceased donor organ with a high level of tissue compatibility had been identified. Andrews underwent the three-hour transplant surgery the following day, making him the first person in the world to successfully transition from a pig kidney xenograft to a human donor kidney. “I’m the first one that went across the bridge,” Andrews told CNN.

Frequently Asked Questions

What is a bridge transplant?

According to researchers at Mass General Brigham, a bridge transplant involves using a temporary organ—such as a genetically modified pig kidney—to keep a patient alive and healthy enough to eventually receive a standard human donor organ.

How many genetic modifications did the pig kidney have?

The kidney used in this case study featured 69 genomic modifications aimed at improving immune system compatibility and reducing viral risks, according to data published in The Lancet.

What happened to the first pig kidney recipient?

The first pig kidney transplant into a living person in 2024 ended after 52 days when the patient died from unrelated heart problems, according to medical records.

What Comes Next for Xenotransplantation Research

While the successful nine-month duration and subsequent human transplant mark a major milestone, researchers caution that the findings reflect a single patient without a comparison group. Clinicians aim to establish long-term safety and durability so that animal organs might eventually serve as destination therapies rather than temporary stopgaps. For now, patients like Andrews demonstrate that animal organs can keep individuals alive long enough to secure a second chance at life through human donation.