In a First, Surgeons Attached a Pig Kidney to a Human, and It Worked

Surgeons in New York have successfully attached a kidney grown in a genetically altered pig to a human patient and found that the organ worked normally, a scientific breakthrough that one day may yield a vast new supply of organs for severely ill patients.

Researchers have long sought to grow organs in pigs that are suitable for transplantation into humans. Technologies like cloning and genetic engineering have brought that vision closer to reality in recent years, but testing these experimental organs in humans has presented daunting ethical questions.

So surgeons at N.Y.U. Langone Health took an astonishing step: With the family’s consent, they attached the pig’s kidney to a brain-dead patient who was sustained on a ventilator, and then followed the body’s response while taking measures of the kidney’s function. It is the first operation of its kind.

The researchers tracked the results for just 54 hours, and many questions remained to be answered about the long-term consequences of such an operation. The procedure will not be available to patients any time soon, as there are significant medical and regulatory...