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 kept alive 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 hurdles to overcome.

Still, experts in the field hailed the surgery as a milestone.

 

The kidney used in the new procedure was obtained by knocking out a pig gene that encodes a sugar molecule that elicits an aggressive human rejection response. 

 

The pig was genetically engineered by Revivicor and approved by the Food and Drug Administration for use as a source for human therapeutics.

Dr. Montgomery and his team also transplanted the pig’s thymus, a gland that is involved in the immune system, in an effort to ward off immune reactions to the kidney.

After attaching the kidney to blood vessels in the upper leg, the surgeons covered it with a protective shield so they could observe it and take tissue samples over the 54-hour study period.

Urine and creatinine levels were normal, Dr. Montgomery and his colleagues found, and no signs of rejection were detected during more than two days of observation.

“This is a huge breakthrough,” said Dr. Dorry Segev, a professor of transplant surgery at Johns Hopkins School of Medicine who was not involved in the research. “It’s a big, big deal.”

 

A steady supply of organs from pigs — which could eventually include hearts, lungs and livers — would offer a lifeline to the more than 100,000 Americans currently on transplant waiting lists, including the 90,240 who need a kidney. Twelve people on the waiting lists die each day.

 

An even larger number of Americans with kidney failure — more than a half million — depend on grueling dialysis treatments to survive. In large part because of the scarcity of human organs, the vast majority of dialysis patients do not qualify for transplants, which are reserved for those most likely to thrive after the procedure.

 

The transplanted kidney was obtained from a pig genetically engineered to grow an organ unlikely to be rejected by the human body. In a close approximation of an actual transplant procedure, the kidney was attached to blood vessels in the patient’s upper leg, outside the abdomen.

The organ started functioning normally, making urine and the waste product creatinine “almost immediately,” according to Dr. Robert Montgomery, the director of the N.Y.U. Langone Transplant Institute, who performed the procedure in September.

Although the kidney was not implanted in the body, problems with so-called xenotransplants — from animals like primates and pigs — usually occur at the interface of the blood supply and the organ, where human blood flows through pig vessels, experts said.

After attaching the kidney to blood vessels in the upper leg, the surgeons covered it with a protective shield so they could observe it and take tissue samples over the 54-hour study period.

Urine and creatinine levels were normal, Dr. Montgomery and his colleagues found, and no signs of rejection were detected during more than two days of observation.

“There didn’t seem to be any kind of incompatibility between the pig kidney and the human that would make it not work,” Dr. Montgomery said. “There wasn’t immediate rejection of the kidney.”"