From Pig to Human: How One Man's Experimental Kidney Transplant Opened a New Door

Tim Andrews made medical history twice in one year—first as one of the world's first recipients of a genetically modified pig kidney, then as the first person in that pioneering group to successfully receive a human kidney afterward. The 67-year-old from New Hampshire lived with his pig kidney, which he named Wilma, for a record-breaking 271 days before his body rejected it and he received a near-perfect human kidney match.

Why Are Pig Kidneys Being Used for Human Transplants?

The experimental procedure, called xenotransplantation, represents a potential solution to America's severe organ shortage crisis. At any given time, more than 100,000 people in the United States are waiting for an organ transplant, with about 80% needing kidneys. However, the reality is even more stark—of the more than 800,000 people with kidney failure, nearly 70% are stuck on dialysis, a grueling treatment that tries to compress into just a few hours per week the work healthy kidneys do around the clock.

"Dialysis is not able to reproduce what the body needs in terms of clearing the waste," said Dr. Leonardo Riella, medical director of kidney transplantation at Mass General Brigham hospital and Andrews' doctor. "It has a huge burden on the patient, both in their quality of life, but most importantly on their health."

What Made Andrews' Case So Groundbreaking?

Andrews' journey began when his diabetes led to end-stage kidney disease. Like many patients, he found dialysis nearly unbearable—hooked up to a machine three days a week for up to six hours at a time. The treatment left him exhausted, nauseous, and suffering from what he called "dialysis foggy" thinking. Six months after starting dialysis, he had a heart attack.

The pig kidney transplant on January 25, 2025, changed everything immediately. "I was clear," Andrews remembered. "I was not what I call dialysis foggy. I wasn't tired or anything. All of a sudden I had energy." The genetically modified pig organs are specially engineered to control for rejection and size, making them potentially compatible with human bodies.

However, maintaining the pig kidney required an intensive regimen that included several challenging aspects:

• Daily Medication Load: Andrews took 52 pills every day to help keep his immune system from rejecting Wilma
• Constant Monitoring: His medical team tracked his progress closely, watching for signs of rejection over nine months
• Infection Management: He developed two infections during the process, requiring adjustments to his immunosuppressant protocol

What Does This Mean for Future Kidney Patients?

When Andrews' body eventually rejected the pig kidney in October, the research team gained valuable insights. Mike Curtis, president and CEO of eGenesis—the company that provided the donor pig—explained that it was a slow rejection scientists could see developing for months. "We have a much better idea of what was causing that low-level rejection, so we can then tune the suppression," Curtis said.

The experience has already improved treatment protocols. Since Andrews' human kidney transplant in January 2025, Mass General and eGenesis have performed two more xenotransplants and are preparing to start a clinical trial. Dr. Robert Montgomery, director of the NYU Langone Transplant Institute, believes xenotransplant will become a viable solution for patients within the next five years.

For Andrews, the experimental treatment was life-saving. "If I didn't take Wilma, I'd have been dead by now," he said. "I wasn't gonna make it another year. I'm looking at years now. I can think ahead." His new human kidney requires about one-third of the immunosuppressant medication he needed for the pig kidney, and he's already planning to advocate for organ donation and share his unique story with the world.