I never imagined I'd be going back to having just a normal life.
For seven years, Oscar Larrainzar lived without a functioning bladder, tethered to dialysis and the slow diminishment that chronic illness imposes on a life. In May 2025, at UCLA Health, surgeon Dr. Nima Nassiri performed what medicine had long considered impossible — a human bladder transplant — and one year later, Larrainzar swims with his daughter and calls his life normal again. The achievement belongs not only to one patient but to the long arc of surgical imagination: Nassiri has since completed additional transplants, and a clinical trial is underway, opening a door that end-stage bladder disease had kept firmly shut.
- A man who spent seven years without a functioning bladder has returned to work, travel, and swimming with his daughter — the human measure of a medical milestone.
- Traditional bladder reconstruction using intestinal tissue carries chronic risks that have long left terminal bladder patients with diminished lives and few alternatives.
- Nassiri's technique transplants the bladder as a vascularized organ with its own blood supply — a method borrowed from kidney and heart transplantation that no surgeon had ever applied to the bladder before.
- An early complication — a urine leak that became infected — forced a second surgery, but the setback became a lesson: subsequent transplants abandoned the drainage tubes that caused it.
- A second patient lost his transplanted bladder to complications, then received a second one — an unprecedented re-transplant that suggests even failed grafts may have a second chance.
- With a third patient urinating independently and two more transplants planned for 2026, a new surgical field is taking shape around patients who previously had nowhere left to turn.
Oscar Larrainzar was 41 years old, seven years into life without a functioning bladder, when he became the first human to receive a bladder transplant. Performed in May 2025 at UCLA Health by urologic transplant surgeon Dr. Nima Nassiri, the procedure also included a kidney transplant for a man who had been on dialysis and whose quality of life had narrowed to the dimensions of his medical equipment. One year later, he is 43, back at work, and swimming with his daughter for the first time since she was an infant.
What makes Nassiri's approach revolutionary is its departure from decades of surgical convention. Patients with terminal bladder disease had long been treated through reconstruction using the patient's own intestinal tissue — a method that works imperfectly, carrying risks of chronic infection and metabolic complications. Nassiri instead transplanted the bladder as an independent organ with its own blood supply, the way a kidney or heart is moved from donor to recipient. No protocol existed. He and his team had to define the benchmarks for success themselves.
The first months were not without difficulty. On day 25, Larrainzar developed a urine leak from a backup drainage tube, which became infected and required a second surgery. The team studied the failure and eliminated those tubes from future procedures. By six months, Larrainzar's bladder held 600 milliliters — the full capacity of a healthy organ — and the results were published in The Lancet.
The second transplant, performed in February 2026, brought a different kind of lesson. The kidney succeeded; the bladder did not and had to be removed. Facing an entirely new question — could a bladder be re-transplanted in the same patient? — Nassiri's team attempted it and found the answer was yes. A third patient is now urinating independently nearly two months after surgery. Two more transplants are planned for later in 2026. Nassiri has been measured in how he describes what has been built. But for patients with end-stage bladder disease, the opening of even one new door is, as he has suggested, everything.
A year ago, Oscar Larrainzar woke from surgery with something he hadn't possessed in seven years: a functioning bladder. He was 41 then, tethered to dialysis, carrying medical equipment that had become the weight of his life. Now 43, he's back at work. Last month he swam with his 10-year-old daughter for the first time since she was an infant. He took a family trip to Las Vegas. He no longer needs a catheter. He lives, as he put it, a normal life.
Larrainzar was the first human to receive a bladder transplant. The surgery happened in May 2025 at UCLA Health, performed by Dr. Nima Nassiri, a urologic transplant surgeon who had spent years imagining a procedure that the medical field had deemed impossible. Nassiri didn't just transplant a bladder into Larrainzar—he transplanted a kidney as well, giving a man who had been dying the chance to live again. One year later, the results are clear enough that Nassiri has already completed a second bladder transplant, and a third patient is recovering well, urinating on his own without assistance.
What makes this work revolutionary is not merely that it succeeded, but how it succeeded. For decades, surgeons treating patients with terminal bladder disease had relied on a single approach: reconstructing a new bladder from the patient's own intestinal tissue. The method works, after a fashion, but it carries serious risks—chronic infections, metabolic complications, the slow erosion of quality of life. Nassiri's innovation was to transplant the bladder as an independent organ, complete with its own blood supply, the way a kidney or heart is transplanted. No one had ever done this before. There was no playbook. Before operating on Larrainzar, Nassiri and his team had to invent the benchmarks for success from scratch.
The first months tested that invention. On day 25 post-surgery, Larrainzar developed a urine leak from a drainage tube placed as a backup system. The leak became infected. Nassiri operated again to close it and remove the tube. It was a setback, but it was also data. Nassiri and his team studied what went wrong and made a decision: future transplants would not use those secondary tubes. Larrainzar healed quickly after the second procedure, and by the six-month mark—the milestone detailed in a peer-reviewed paper published in The Lancet on June 23—he was holding 600 milliliters of urine, the full capacity of a healthy bladder. At 30 days post-surgery, he had already surpassed the team's initial benchmark of 200 milliliters.
The second patient's case proved instructive in a different way. Like Larrainzar, this patient received both a kidney and a bladder in February 2026. The kidney took. The bladder developed a complication that forced its removal. The patient recovered, his new kidney functioning well, and the team faced an unprecedented question: could they attempt another bladder transplant in the same person? They didn't know. But they tried, and they discovered the answer was yes. Nassiri expects that second attempt to succeed, which would mark yet another first—a re-transplant of a human bladder, proof that even if a transplanted bladder fails, salvage may be possible.
The third patient, now nearly two months out from surgery, is urinating independently without a catheter. Nassiri has identified two more patients for transplants later in 2026 as part of the ongoing clinical trial. In a research paper and in interviews, Nassiri has been careful not to oversell what has been accomplished. "It's not a fairy-tale story," he said. "These things happen." But what has happened—what continues to happen—is the opening of a door that was thought to be locked. For patients with end-stage bladder disease, a condition that has offered little hope for a return to normal life, that door is everything.
Citas Notables
We learn from each procedure. Our hope is to help many more patients—especially those with end-stage bladder disease who haven't had much hope for a normal life.— Dr. Nima Nassiri
To be honest, I didn't believe it would happen—that the surgery would be so successful and I would wake up and not even need a catheter.— Oscar Larrainzar
La Conversación del Hearth Otra perspectiva de la historia
Why does a bladder transplant matter more than, say, perfecting the intestinal reconstruction method that's been used for decades?
Because reconstruction from intestine works, but it's a compromise. You're building a pouch from tissue that wasn't designed to be a bladder. It gets infected. It causes metabolic problems. You're trading one disease for another. A transplanted bladder is an actual bladder, with its own blood supply, its own nerve endings eventually. It's not a workaround—it's restoration.
Larrainzar had been without a functioning bladder for seven years. What does that actually mean for a person's life?
It means you're dependent on catheters or external collection systems. You can't swim with your daughter. You can't travel without planning around medical equipment. You're not just sick—you're tethered. Seven years of that. Then suddenly you're not.
The second patient's bladder failed. How is that not a disaster for the whole program?
It would be, if it meant the end. But Nassiri's team learned something crucial: they could try again. That changes everything. It means even failure isn't final. It means the field has a path forward even when things go wrong.
What was the complication on day 25 with Larrainzar?
A backup drainage tube started leaking urine, and the area got infected. It required a second surgery. But that failure taught them something—they don't need those backup tubes in future transplants. Every problem becomes a lesson.
How confident is Nassiri that this will become standard treatment?
He's careful about that. He says "it's not a fairy-tale story." But he's already planning more transplants. He's identifying patients. He's thinking about re-transplantation protocols. That's not the language of someone who thinks this was a one-time miracle. That's the language of someone building a field.