Transplants from animals to humans: a near reality?

Tim Andrews, a 66-year-old American with kidney failure caused by type 2 diabetes, has been at the centre of the xenotransplant case with the longest survival recorded so far. With only a 9% chance of receiving a human kidney within five years and a more than 40% risk of dying or being removed from the waiting list, doctors at Mass General Brigham (Boston) transplanted, in January 2025, a pig kidney with 69 genetic modifications to reduce rejection. 

The organ worked immediately and kept him off dialysis for 271 days, until some lesions made it necessary to remove it. After a few more months on dialysis, at the beginning of 2026 he received a human kidney which, according to a study published in The Lancet, is still functioning normally.

The future of xenotransplants

The case confirms that xenotransplants have entered a new phase, marked by a technological race between the United States and China. The clinical company ClonOrgan, in fact, has kept a pig kidney functioning for more than 200 days, while others have carried out the first liver and lung transplants from pigs to people.

To date, around twenty xenotransplants have already been carried out worldwide – most of them kidney, and also heart, liver and lung – almost all of an experimental nature. Specialists stress that, despite the advances, this technique is still far from matching the results of transplants between humans, and doubts remain about safety, durability of the organs, risk of infections and cost. Even so, given the chronic shortage of organs, many researchers see pigs as the most viable donor source in the medium term.