The first ‘across the bridge’: Man who received experimental pig kidney transplant now has a human organ

Tim Andrews, who received an experimental pig kidney transplant, now has a human organ. Amanda Sealy/CNN via CNN Newsource

One year ago, Tim Andrews was among the world’s first recipients of a genetically modified pig kidney. Now, he is the first in that small group of pioneers to go on to receive a human kidney.

“I’m the first one that went across the bridge. … I’m the only person in the world that’s ever had a pig kidney and then had a human kidney after it,” he told CNN from the hospital on Thursday. “Nobody’s ever been across that bridge. That is cool!”

Andrews, who has diabetes and was living with end-stage kidney disease, received a pig kidney on January 25, 2025, and lived with it for a record 271 days. After his body rejected the organ, it was removed in October, and Andrews returned to dialysis — a grueling process that kept him alive but made him so miserable it had driven him to the experimental xenotransplant in the first place.

“I cried,” said Andrews, 67. He told his family he didn’t expect to make it through the year.

But at nearly midnight on January 12, Mass General Brigham called to tell him that a human kidney — a near-perfect match — had been identified. He was scheduled for transplant surgery at 8 a.m. the following day.

Andrews now expects to be discharged to his home in New Hampshire on Friday, just days after the milestone organ transplant that made him a living example of the promise of xenotransplantation: Organs from animals may help keep humans alive and healthy enough for a longer-term solution and a new shot at life.

An answer to organ shortages

Xenotransplantation – the transplant of different species’ organs - has been touted as a possible solution to the current shortage of organ donors. The transplanted pig organs are genetically modified to control for rejection and size.

At any given time in the US, there are more than 100,000 people waiting for an organ, about 80 per cent of them in need of kidneys. But only the sickest of the sick are listed; just 1 in 8 patients with end-stage renal disease are on the waitlist.

Of the more than 800,000 people with kidney failure, nearly 70 per cent are on dialysis. But dialysis is trying to compress into just a few hours every week the work that the body typically does 24/7. The five-year survival rate for patients on dialysis hovers around 40 per cent.

“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.”

Andrews was hooked up to a dialysis machine three days a week for up to six hours at a time. Six months after starting dialysis the first time, he had a heart attack. “It takes a toll on you emotionally and physically; you just get exhausted and I got sick. I was throwing up all the time,” he said.

While organs remain in short supply, Riella sees xenotransplantation as a solution.

“Even if it is a bridge,” Riella said, “it would be better than (Tim) just staying on dialysis.”

To prepare Andrews for the human transplant, the team at Mass General tested Andrews for new antibodies that could potentially react with the new human kidney and found none. His most recent transplant took just about three hours, and he said his new immunosuppressant regimen is about a third of what he took when he had a pig kidney.

‘This will do something for humanity’

For Andrews, getting the xenotransplant wasn’t just a matter of hope away from dialysis but hope for patients with end stage renal disease.

“This will do something for humanity,” he told CNN Chief Medical Correspondent Dr. Sanjay Gupta in the documentary “Dr. Sanjay Gupta Reports: Animal Pharm.”

Immediately following his xenotransplant last year, Andrews felt different. “I was clear. I was not what I call dialysis foggy. I wasn’t tired or anything. All of a sudden I had energy,” he remembered.

But the path forward had ups and downs. Andrews took 52 pills a day to help keep his pig kidney, which he named Wilma, and immune system in agreement. Ultimately, over the course of nine months, the kidney began showing signs of rejection. He had two infections. Riella said they adjusted Andrews’ immunosuppressant protocol, but the kidneys had become damaged in the process.

“There was some damage to the filters of the kidney that unfortunately, were not reversible,” Riella said. Ultimately, they removed Wilma, and Andrews had to return to dialysis.

Mike Curtis, president and CEO of eGenesis, the company that provided the donor pig for Andrews’ kidney, said it was a slow rejection that scientists could see coming for months.

“We just could not figure out how to how to push it back,” Curtis said.

But biopsies and research into Andrews and the pig kidney may have helped them pinpoint what led to the rejection, which may help future kidney recipients.

“We have a much better idea of what was causing that low level rejection, so we can then tune the suppression,” Curtis said.

Andrews’ experience has helped refine treatment for the next xenotransplant patients. Since his surgery in January 2025, Mass General and eGenesis have teamed up to perform two more xenotransplants before starting a clinical trial in the near future.

An alternative to dialysis

But Riella also sees the xenotransplant as a success for Andrews. Wilma was able to keep him off dialysis for nine months. After Andrews returned to dialysis, his overall function dropped again, and he was losing muscle mass and energy.

At this point, Riella said, the comparison of xenotransplant may not be to a human kidney but to dialysis. “It’s a much better treatment to maintain the kidney function compared to what dialysis is able to offer,” he said. “Our goal is to basically ban dialysis as a long-term treatment.”

But an alternative to dialysis isn’t the end goal, said Dr. Robert Montgomery, director of the NYU Langone Transplant Institute. Montgomery wasn’t involved in Andrews’ care but has also been at the front of the xenotransplant field.

“As this gets better and xenografts last longer, it will be a destination,” said Montgomery, who was the first doctor to transplant pig organs into brain- dead patients and is leading the first FDA-cleared clinical trial into xenotransplant at NYU.

Montgomery believes that xenotransplant will be a viable solution for patients within the next five years. “In the future I think a single patient with renal failure will cycle through both xenografts and allografts throughout their lifetimes.”

Riella says it’s impossible to know what would have happened to Andrews if he had not tried an experimental xenotransplant. But Andrews said he has no doubt that Wilma was key to getting him to this point.

“If I didn’t take Wilma, I’d have been dead by now. I wasn’t gonna make it another year,” Andrews said. “I’m looking at years now. I can think ahead.”

What he’s thinking of now is sharing his own story and urging others to become organ donors.

“People need to step up and help,” Andrews said.

In a message Andrews posted to social media on Friday, he thanked the family of his donor, who has not been identified.

“I grieve with you. It’s got to tear you apart, but I’m here to tell you, the donation of a kidney has saved my life, and you have given hope to millions. Your family member is a hero. He’s a hero, not just to me, but to the entire world,” Andrews said.

“I’ll never be able to repay you, but I promise you it’ll be in my heart. And it will be cared and loved for for as long as I live, and I will spend my life basically preaching, and I’m not a preacher, about what this love did.”

By Nadia Kounang, CNN