Scientists took the first steps toward pig-to-human kidney transplants

For the first time, surgeons have successfully attached a kidney from a genetically modified pig to a human patient – a major scientific breakthrough, and one that could open a new way to deliver organs to sick people.

Scientists obtained the kidney of a pig that was genetically modified so that it did not produce a sugar called alpha-gal, which the human immune system attacks and is said to trigger the organ to be rejected by the body. NYU surgeons attached the organ to a brain-dead patient on a ventilator whose family agreed to the experimental procedure. It was connected outside of his body to the blood vessels in his leg and observed over a 54 hour period.

The recipient’s body did not immediately reject the kidney, and the kidney functioned normally during the hours it was attached. “There did not appear to be any incompatibility between the pig kidney and the human that would prevent it from functioning,” said Robert Montgomery, director of the NYU Langone Transplant Institute, according to The New York Times. “There was no immediate rejection of the kidney.”

There are still a lot of open questions: it is not clear whether the organ would last for a long period of time inside the body. While the kidney has been functioning during the time it was attached, organ rejection can occur over the years – and can occur even if the donor and recipient are a perfect match. Details of the procedure have not been reviewed or published in a medical journal.

Experts are also examining the ethical implications of this type of animal-to-human procedure. Karen Maschke, researcher at the Hastings Center, receives a grant to develop ethical and policy recommendations for clinical trials of these transplants.

But the procedure was still a historic milestone in efforts to perform animal-to-human transplants, called xenotransplantation. Animal heart valves have been used in human procedures for decades, but these can be chemically treated to kill living cells and prevent rejection. Organs, made up of living tissue, are more complicated. Supporters of these efforts envision a constant supply of animal organs, which could help the thousands of people on waiting lists for transplants. They could be a lifeline for the hundreds of thousands of people with kidney failure who depend on dialysis.

The kidney used in this procedure was produced by the company Revivicor. The Food and Drug Administration (FDA) approved its genetically modified pigs for therapeutic purposes and for human consumption in December 2020. (Some people are allergic to alpha-gal sugar, and the meat from these pigs may be safe for them. .) The FDA would still need to examine all medical products – like organs – before they can be used medicinally. The company said in April it hoped to start clinical trials using its animal organs for transplants “within a year or two.”