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Surgeons successfully test pig-to-human kidney transplant

A surgical team at the hospital in New York examines a pig kidney attached to the body of a brain-dead recipient for any signs of rejection.
A surgical team at the hospital in New York examines a pig kidney attached to the body of a brain-dead recipient for any signs of rejection.   -   Copyright  AP Photo
By AP

A pig’s kidney has been transplanted into a human and in a medical first was not immediately rejected by the patient’s immune system.

Scientists watched the animal’s organ begin to work as part of a three day experiment which took place at the end of September, a small step in the decades-long quest to one day use animal organs for life-saving transplants.

Pigs have been the most recent research focus to address the organ shortage but a sugar in pig cells, foreign to the human body, causes immediate organ rejection.

The kidney for this experiment came from a gene-edited animal, engineered to eliminate that sugar and avoid an immune system attack.

“It had absolutely normal function,” Dr. Robert Montgomery, who led the surgical team last month at NYU Langone Health, told the Associated Press. “It didn’t have this immediate rejection that we have worried about.”

Surgeons attached the pig kidney to a pair of large blood vessels outside the body of a brain-dead patient so they could observe it for two days. The kidney did what it was supposed to do — filter waste and produce urine — and didn't trigger rejection.

The family of the patient had given their consent for the experiment and researchers kept the woman’s body going on a ventilator.

The woman had wished to donate her organs, but they weren’t suitable for traditional donation.

The family felt “there was a possibility that some good could come from this gift,” Montgomery said.

Montgomery himself received a transplant three years ago, a human heart from a donor with hepatitis C because he was willing to take any organ.

“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.

The history of pig-human transplants

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.

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.

Pig heart valves also have 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.

What next?

In December, the Food and Drug Administration approved the gene alteration in the pigs as safe for human food consumption and medicine.

But the FDA said developers would need to submit more paperwork before pig organs could be transplanted into living humans.

“This is an important step forward in realising the promise of xenotransplantation, which will save thousands of lives each year in the not-too-distant future,” said United Therapeutics CEO Martine Rothblatt in a statement.

Experts say tests on nonhuman primates and last month’s experiment with a human body pave the way for the first experimental pig kidney or heart transplants in living people in the next several years.

Raising pigs to be organ donors feels wrong to some people but it may grow more acceptable if concerns about animal welfare can be addressed, Karen Maschke told the Associated Press. She is a research scholar at the Hastings Center, who will help develop ethics and policy recommendations for the first clinical trials under a grant from the National Institutes of Health.

“The other issue is going to be: Should we be doing this just because we can?” Maschke said.