A year after the first-ever human bladder transplant, the trailblazing surgeon has successfully completed a second bladder transplant.
This paves the way for a surgical field that was previously unfeasible.
Dr Nima Nassiri, a urologic transplant surgeon, leads the groundbreaking UCLA Health clinical trial, which began in May 2025 by transferring a kidney and a bladder into a 41-year-old cancer survivor.
At the time, Oscar Larrainzar was on dialysis and hadn’t had a functioning bladder for seven years. Following the first-of-its-kind surgery, he now has full use of his new bladder.
Dr Nassiri has led a new research paper detailing the patient’s progress at the critical six-month post-transplant milestone.
The work, the first-ever account of a human bladder transplant, was peer-reviewed before publication in The Lancet in June.
Dr Nassiri has already identified patients for two additional bladder transplants in 2026, as part of the ongoing clinical trial at UCLA Health.
He said: ‘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 of a normal life.’
The transplant was the first to transfer a bladder as an independent, vascularised organ with its own blood supply.
The established standard is to construct a bladder from intestinal walls, which can lead to serious infection or metabolic complications.
In the new study, Nassiri outlines how, because the transplant was the first of its kind, his team had to define benchmarks for success before the operation.
After 30 days, Larrainzar was able to hold 270 ml of urine (almost 7 oz), surpassing the 200 ml benchmark; by six months, he was holding 600 ml. That’s 20 oz, the full capacity of a normal, healthy bladder.
Nassiri’s initial two surgeries – the first in May 2025 and the second in February 2026 – transplanted both a bladder and a kidney into each patient.
In the second enrolled patient, who ultimately received a successful kidney transplant, the new bladder developed a complication that led to its removal.
The patient recovered; his new kidney is functioning well, and the team is planning a potential second attempt to transplant a bladder.
Nassiri’s third patient is recovering well from a combined kidney and bladder transplantation, and is almost two months out from surgery, urinating by himself without the need for a catheter.
Nassiri noted that the patient with a failed bladder following a kidney transplant presented a learning opportunity. Initially unsure whether a re-transplant was possible, the team was surprised to find they could attempt it. He expects success and views this as a milestone – the first human bladder re-transplant.
He emphasised that, although rare, such cases demonstrate that salvage is possible after bladder failure and can shape future treatments and protocols.
