According to the director of the NYU Langone Transplant Institute, Dr. Robert Montgomery, who performed the procedure in September, 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 a brain-dead patient who was on a ventilator.
The kidney, attached to blood vessels in the upper leg outside the abdomen, started functioning normally, making urine and the waste product creatinine almost immediately, Montgomery said.
Although the organ was not implanted in the body, problems with so-called xenotransplants — from animals like primates and pigs — usually occur at the interface of the human blood supply and the organ, where human blood flows through pig vessels, experts said.
The fact that the organ functioned outside the body is a strong indication that it will work in the body, Dr. Montgomery said.
“It was better than I think we even expected,” he said. “It just looked like any transplant I’ve ever done from a living donor. A lot of kidneys from deceased people don’t work right away, and take days or weeks to start. This worked immediately.”
Explaining how the surgery was performed, Montgomery said, 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.
The team of researchers also transplanted the pig’s thymus, a gland that is involved in the immune system, 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.
“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 an immediate rejection of the kidney.”
Reacting to this development, health experts say there are many questions to be answered about the long-term consequences of the transplant.
“We need to know more about the longevity of the organ,” said a professor of transplant surgery at Johns Hopkins School of Medicine, Dr. Dorry Segev, who was not involved in the research. Nevertheless, he admitted this to be a huge breakthrough.
source: HealthWise
