Pig's kidney brings transplants for humans a step closer

NEW YORK－Scientists temporarily attached a pig's kidney to a human body and watched it begin to work, a small step in a decadeslong quest to one day use animal organs for lifesaving transplants.

The procedure done at NYU Langone Health in New York City involved use of a pig that had genes altered so that its tissues no longer contained a molecule known to trigger almost immediate rejection.

The recipient was a brain-dead patient with signs of kidney dysfunction whose family consented to the experiment before she was due to be taken off life support, researchers said.

For three days, the new kidney was attached to her blood vessels and maintained outside her body, giving researchers access to it.

Test results of the transplanted kidney's function "looked pretty normal", said transplant surgeon Robert Montgomery, who led the study.

He said the kidney made "the amount of urine that you would expect" from a transplanted human kidney, and there was no evidence of the vigorous early rejection seen when unmodified pig kidneys are transplanted into nonhuman primates.

The recipient's abnormal creatinine level－an indicator of poor kidney function－returned to normal after the transplant.

This research is "a significant step", said Andrew Adams of the University of Minnesota Medical School, who was not part of the research work. It will reassure patients, researchers and regulators "that we're moving in the right direction".

The dream of animal-to-human transplants, or xenotransplantation, goes back to the 17th century with stumbling attempts to use animal blood for transfusions. By the 20th century, surgeons were attempting transplants of organs from baboons into humans, notably Baby Fae, a dying infant who lived 21 days with a baboon heart.

With no lasting success and much public uproar, scientists turned from primates to pigs, tinkering with their genes to bridge the species gap.

Fewer ethical issues

Pigs have advantages over monkeys and apes. They are produced for food, so using them for organs raises fewer ethical concerns. Pigs have large litters, short gestation periods and organs comparable to humans.

Several biotech companies are in the running to develop suitable pig organs for transplant to help ease the human organ shortage. More than 90,000 people in the United States wait in line for a kidney transplant.

Pig heart valves have also been used successfully for decades in humans. The blood thinner heparin is derived from pig intestines. Pig skin grafts are used on burns and Chinese surgeons have used pig corneas to restore sight.

Researchers have been working for decades on the possibility of using animal organs for transplants, but have been stymied over how to prevent immediate rejection by the human body.