For the first time ever, a pig’s kidney worked successfully on a human. While the experiment lasted only 54 hours, and much more research is necessary, experts say it represents a major step forward in the potential use of animal organs for humans.
A team led by Dr. Robert Montgomery at NYU Langone Health performed the procedure last month, USA Today reported. Pig organs are usually rejected by the human body, because they contain a sugar molecule called alpha-gal that our bodies do not recognize, according to the Associated Press. This pig, however, had been genetically-engineered without that sugar. Its kidney was then attached to blood vessels outside the body of a patient who had died, but was kept on a ventilator. The pig’s thymus was also transplanted, as an attempt to ward off any potential negative effects in the immune system.
During the two days the doctors observed the transplant, the kidney performed as a normal kidney should: it filtered waste, created urine, regulated the patient’s abnormal creatinine level, and wasn’t rejected by the host body.
“It was better than I think we even expected,” Montgomery told the New York Times. “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.”
If further research goes well, genetically-engineered pigs “could potentially be a sustainable, renewable source of organs,” he went on, calling the pigs “the solar and wind of organ availability.”
The transplant represents “a significant step,” Dr. Andrew Adams of the University of Minnesota Medical School told AP. (It is, however, worth remembering that the research has not been peer-reviewed.)
There’s a huge need for kidney transplants in Canada and around the world. In 2019, the last year for which we have data, 77 per cent of the 4,419 Canadians on a waiting list for a transplant were waiting for a kidney. Kidney failure can be fatal: we need kidneys to cleans toxins and waste from our body in order to live. Current wait times for a kidney can be anywhere from a few months to several years, according to the Canadian Kidney Foundation. And because donor kidneys are rare, many people with kidney disease don’t qualify to receive donations, and instead rely on dialysis — a process that either involves blood being removed from the body, filtered, and then put back in, or else cleansing fluid inserted into the abdomen with a catheter.
Attempts to use animal organs as life-saving transplants for humans, or xenotransplantation, go back to the 1600s, AP reports. In 1963 and 1964, a doctor named Keith Reemtsma transplanted several humans with chimpanzee kidneys. All of the patients died of infection, but many people were surprised by how long it took — the most successful transplant was in a woman who lived another nine months after the surgery.
Twenty years later, in 1984, a baby girl in California was born with an underdeveloped heart. Because infant transplant hearts are so rare, “Baby Fae” received a heart transplant from a baboon. She lived for 21 days — two weeks longer than any other human had lived after receiving an animal heart.
Around this time, scientists started to shift their focus to pigs for a few reasons: many of their organs are similar to humans, and they have large litters and short gestation periods. And as AP points out, there are fewer ethical concerns about transplantation around pigs than primates, since we already raise pigs for food.
The patient who received the kidney had wanted to donate her organs, but they weren’t suitable. Her family thought being used in this kind of research was the next best thing, Montgomery told AP.
He also said he had received a transplant himself several years ago: a human heart from a donor with hepatitis C.
“I was one of those people lying in an ICU waiting and not knowing whether an organ was going to come in time,” he said.