Scientists temporarily attached a pig’s kidney to a human body and watched it begin to work, a small step in the decades-long quest to one day use animal organs for life-saving transplants.

Recently, pigs were the focus of research to solve the organ shortage. But, one hurdle is: The sugar found in the pig cells causes organ rejection. This kidney was obtained from an engineered animal with a genetic modification to reduce sugar levels and protect the immune system.

To observe the organ for two days, doctors attached it to large blood vessels that were outside of the deceased person’s body. The kidney did what it was supposed to do — filter waste and produce urine — and didn’t trigger rejection.

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

This research is “a significant step,” said Dr. Andrew Adams of the University of Minnesota Medical School, who was not part of the work. It will reassure patients, researchers and regulators “that we’re moving in the right direction.”

The dream of animal-to-human transplants — or xenotransplantation — goes back to the 17th century with stumbling attempts to use animal blood for transfusions. In the early 20th century surgeons attempted to transplant organs from baboons onto humans. This included Baby Fae who was an infant that died after being given a baboon heart for 21 days.

NYU Langone Health’s September 2021 photo shows a surgeon examining a pig kidney that was attached to the body a deceased recipient in order to determine if there are any signs of rejection. (Joe Carrotta/NYU Langone Health via AP
Source: Associated Press

Scientists tried to make the gap between species and race close to their natural habitat, but with no success, much controversy ensued.

The advantages of pigs over monkeys, apes are numerous. Pigs are bred for their food and organs can be used for them. This means that there is less ethical concern. Large litter sizes, shorter gestation times and comparable organs to human beings make pigs a popular choice.

The use of pig heart valves in human beings has been successful for years. Heparin, a blood thinner made from pig intestinal juices is also derived. For burns, pig skin grafts can be used. Chinese surgeons also use pig corneas for sight restoration.

In the NYU case, researchers kept a deceased woman’s body going on a ventilator after her family agreed to the experiment. 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 received an organ transplant from his donor three years back. It was a human heart that he had donated to him with hepatitis C. Montgomery said he would 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.

Numerous biotech firms are working on developing suitable pig organs that can be transplanted to alleviate the shortage of human organs. Over 90,000. Americans have a right to a kidney transplant. Every day, 12 die while waiting.

Revivicor is now a profitable subsidiary of United Therapeutics. This company engineered the 100-strong herd at an Iowa facility.

Alpha-gal is a sugar that triggers an attack by the immune system in the pigs.

December saw the Food and Drug Administration approved the gene alterationRevivicor Pigs are considered safe for humans to eat and use as medicine.

The FDA however stated that the FDA would require developers to provide additional documentation before transplanting pig organs into humans.

“This is an important step forward in realizing 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.

While raising pigs as organ donors may seem wrong for some, it could become acceptable in the future if there are concerns about animal welfare. Karen Maschke is a research scholar at Hastings Center and will be helping to develop ethical guidelines and policies to guide the first clinical trials with a grant from National Institutes of Health.

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


The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. All content is the sole responsibility of the Associated Press.


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