One year ago, Tim Andrews stepped into medical history as one of the first people in the world to receive a genetically modified pig kidney. Today, he has crossed an even rarer milestone — becoming the first among those pioneers to later receive a human kidney transplant.
From his hospital bed, Andrews described the moment with awe and disbelief. “I’m the first one who went across the bridge,” he said. “I’m the only person in the world who’s had a pig kidney and then a human kidney afterward. Nobody’s ever crossed that bridge before. That’s pretty amazing.”
For Andrews, 67, the journey began out of desperation. Living with diabetes and end-stage kidney disease, he received the experimental pig kidney on January 25, 2025. Against the odds, the organ functioned for a record 271 days. When rejection finally set in, the kidney was removed in October, and Andrews returned to dialysis — the exhausting routine he had hoped never to face again.
“I cried,” he recalled. “I told my family I didn’t think I’d make it through the year.”
Then, just before midnight on January 12, everything changed. Doctors from Mass General Brigham called with unexpected news: a near-perfect human kidney match had become available. By 8 a.m. the next morning, Andrews was in surgery.
Now, only days later, he is preparing to return home to New Hampshire — living proof that xenotransplantation may offer not just survival, but a bridge to a longer, healthier future.
A Crisis of Short Supply
Organ shortages remain one of medicine’s most urgent challenges. In the United States alone, more than 100,000 people wait for transplants, and nearly 80% of them need kidneys. Yet only a fraction of patients with kidney failure ever reach the waitlist.
For the nearly 70% of kidney-failure patients on dialysis, survival is uncertain. Dialysis attempts to replace around-the-clock kidney function in just a few hours each week — an imperfect and punishing substitute. Five years after starting dialysis, only about 40% of patients are still alive.
“Dialysis cannot truly replicate what the kidneys do,” explained Dr. Leonardo Riella, Andrews’ transplant physician. “It places a heavy burden on patients — physically, emotionally, and medically.”
For Andrews, dialysis meant hours attached to a machine three times a week, followed by nausea, exhaustion, and eventually a heart attack. “It wears you down,” he said. “You’re constantly sick and drained.”
That suffering pushed him toward the experimental option that changed everything.
Hope from an Unlikely Source
Xenotransplantation — transplanting organs from animals into humans — has long been seen as a possible solution to donor shortages. By genetically modifying pigs to reduce rejection risks, researchers hope to create a steady supply of organs for patients who cannot wait.
When Andrews received his pig kidney, which he affectionately named Wilma, the results were immediate. “I wasn’t foggy anymore,” he said. “I had energy again. I felt clear.”
For nine months, Wilma kept him off dialysis. Though rejection eventually damaged the kidney beyond repair, the experience proved invaluable. Doctors learned more about immune responses, refined medications, and gained insights that could improve outcomes for future patients.
“This was not a failure,” said Riella. “Compared to dialysis, xenotransplantation gave Tim months of better health and strength.”
A Bridge to the Future
When the time came for Andrews’ human transplant, doctors found no dangerous antibodies that might threaten the new kidney. The surgery lasted just three hours, and his medication regimen is now lighter than before.
Experts believe this hybrid future — alternating between animal and human organs — could soon become standard. Dr. Robert Montgomery of NYU Langone predicts xenotransplants may become routine within five years.
“In the future,” he said, “patients may cycle through both animal and human organs over their lifetimes.”
For Andrews, the science is personal. He believes Wilma gave him the strength to survive long enough for a human kidney. “If I hadn’t taken that chance, I’d be dead by now,” he said. “Now I’m thinking in years again.”
A Message of Gratitude and Purpose
Today, Andrews is focused on gratitude and advocacy. In a heartfelt message, he thanked the family of his donor — an anonymous hero who gave him a second chance.
“You’ve saved my life and given hope to millions,” he wrote. “Your loved one is a hero to the world.”
Now, Andrews plans to share his story wherever he can, urging others to become organ donors.
“People need to step up and help,” he said simply.
From a pig kidney named Wilma to a life-saving human transplant, Andrews’ journey stands as a rare medical first — and a powerful reminder that sometimes, crossing the bridge can change not just one life, but the future of medicine itself.
