ISTANBUL

Scientists have kept a genetically modified pig kidney working inside a brain-dead man for 61 days – and successfully reversed two episodes of rejection, according to two papers published Thursday in Nature.

The findings offer new clues for preventing immune attacks in future transplants involving both animal and human donors.

The recipient, a 57-year-old man who was on life support, received the pig kidney along with the animal’s thymus – a small gland that helps train the immune system.

The procedure, performed last year at NYU Langone Health, marks the longest time a pig organ has worked in a human body after transplantation.

The organ worked immediately after surgery but began failing on day 33. Doctors restored function using plasma exchange, steroids and a complement-blocking drug. A second rejection episode driven by T cells was reversed with immunosuppressants.

In recent years, roughly a dozen patients have received organs from gene-edited pigs, but most transplants failed because the human immune system quickly attacked the donated tissue.

Researchers say understanding exactly which immune cells react and how to stop them is a critical step toward making xenotransplantation – the use of animal organs – viable.