As published in the American Journal of Transplantation, the operation saw the kidneys transferred to the abdomen of a 57-year-old brain-dead man whose own kidneys were fully removed. The study proved that genetically-altered kidneys could work as a replacement for human kidneys. However, the researchers said that some improvements could still be made in certain areas of the procedure.

The kidneys used in the latest procedure were taken from a pig living in a designated pathogen-free facility. Just like a typical human-to-human transplant, they also had to be tissue-matched. During the transplant, the kidneys were attached to the patient’s arteries, veins and bladder.

Importantly, the patient’s body did not reject the pig organs, and no retroviruses were transmitted following the procedure. The kidneys had started producing urine only 23 minutes after being implanted into the patient and continued to do so until the study was terminated three days later. This latest operation is the third breakthrough in xenotransplantation — transplanting an animal organ or product into a human to cure disease. Last year, a research team at New York University succeeded in attaching a modified pig kidney to a brain-dead patient and found it was fully functional.

In January 2022, doctors at the University of Maryland School of Medicine became the first to successfully transplant a genetically-altered pig heart into a living human patient. While animal rights activists like Peta have slammed these developments, the doctors behind them believe they offer an answer to severe organ shortages for people that require transplants. According to the Organ Procurement and Transplantation Network, more than 106,000 people were awaiting transplants in the US as of October 2021. A person was being added to the list every nine minutes, and 17 people died every day while waiting for an organ transplant, kidneys were the most in-demand organ for transplant patients in 2020.