A New Hampshire man lived for a record 271 days with a transplanted pig kidney before doctors replaced it with a human one โ€” in a procedure that's kept him alive ever since and could offer new hope to countless others, researchers said Thursday.

This patient's treatment at Mass General Brigham in Boston marked a significant step forward in xenotransplantation, the transplantation of living organs from one species into another, according to findings published in The Lancet medical journal.

The case shows that a transplanted pig kidney can safely support renal function "while also serving as a bridge" to a subsequent transplant with a human kidney, the study authors wrote.

Tim Andrews, a retired grocery store manager from Barrington New Hampshire, was 66 when he received the pig kidney on Jan. 25, 2025.

Over the following 271 days he needed no dialysis before receiving a human transplant, according to a statement from Mass General.

Over the following 271 days he needed no dialysis before receiving a human transplant, according to a statement from Mass General. (Courtesy Massachusetts General Hospital)

"His case represents the longest dialysis-free survival following porcine kidney xenotransplantation in a living human and the first transition to human kidney transplantation," the hospital said.

Xenotransplantation could soon become a lifesaving option, according to the study's lead author Dr. Leonardo Riella.

"The organ shortage is the greatest crisis we have right now in transplantation," wrote Riella. "We know that the best treatment option for patients with end-stage kidney disease who have developed renal failure is transplantation, but we simply don't have enough human organs to transplant in a timely manner."

Xenotransplantation could soon become a lifesaving option, according to the study's lead author Dr. Leonardo Riella. (Courtesy Massachusetts General Hospital)

More than 100,000 people are on the national transplant waiting list. The vast majority are waiting for a kidney.

For patients like Andrews, using pig kidneys could help buy them enough time to find a human donor.

"Our vision is that xenotransplantation could help address this gap โ€” initially as a bridge to get patients off dialysis while they wait for a human donor kidney, and potentially, as we establish long-term safety and durability, as a destination therapy in its own right," Riella said.

Mass General performed the world's first pig-to-human kidney transplant in 2024.

Richard "Rick" Slayman lived for 52 days before dying of cardiac causes unrelated to the transplant, the hospital said.

When Andrews and doctors first started discussing about the pig transplant, the patient with end stage kidney failure said he was convinced death was near.

But he wanted to try this procedure just for the findings and data it could yield for researchers.

"I didn't think I was going to live through it to be honest. But I wanted to do it for humanity," Andrews told NBC News on Friday.

"I realized, OK I'm a dead man. I'm a dead man walking. So I said to myself, 'What have I done? What have I done with my life? This is an opportunity for me to do something that most people don't get an opportunity to do and that's to help humanity.' "

He added: "I told Dr. Riella, 'This is about learning something. I don't care if I die as long as you learn one thing (from this procedure).' "

The 68-year-old, with three children between that ages of 40 and 46, said the past few years have given him new appreciation for the "little things in life."

He now relishes daily acts of smelling flowers, swimming, riding a bike and fishing.

"Every day I wake up. I'm like, (this is) another (extra) day because I should have been dead a year ago or more," Andrews said.

The patient knows nothing about the kidney donor, other than he was a young man who enjoyed blueberries โ€” a fruit Andrews didn't care much for in his first six decades of life, but now has developed a strange affinity for.

"To know that somebody died way younger and I'm living because of it, that's pretty tough," said an emotional Andrews, his voice trailing off. "I have this new kidney in me and I need to honor it."

This article was originally published on NBCNews.com