Xenotransplantation: pig kidney survives for weeks in human recipient
A pig kidney that has been transferred into a human organism has fulfilled its intended function for two months. This brings the transplantation of animal organs closer to clinical application.
Medical scientists have implanted a pig kidney into a brain-dead patient, which functioned as intended in his body for two months. This is a significant advance on previous experiments: Here, researchers had documented that transplanted pig kidneys can be tolerated by the human organism and produce urine there as intended for a period of just three days. The new success is reported in a press release by a team led by surgeon Robert Montgomery from New York University.
Montgomery and his group implanted the foreign organ into a 58-year-old brain-dead patient who was on artificial respiration in July of this year. The man's family had agreed to the procedure. On 13 September, the predetermined end date of the study, the doctors switched off the artificial respiration and removed the pig kidney again. In the coming weeks, they will analyse the collected data and carry out further tests to find out how the animal organ has changed in the human organism during the two months. They hope to use these findings to improve the transplant procedure so that it can one day be used clinically.
The kidney came from genetically modified "GalSafe" pigs. A gene that is involved in the production of the sugar molecule galactose-alpha-1,3-galactose (alpha-gal) has been switched off in their genome. Alpha-Gal is largely responsible for the human organism fighting and rejecting implanted pig organs. By silencing the corresponding gene, the animal cells are prevented from producing the sugar molecule. Organs from pigs that have been genetically modified in this way last significantly longer after transplantation into the human body because the immune system there attacks them less strongly.
Foreign donation against deficiency
Experts refer to the transfer of animal organs into humans as xenotransplantation (from the Greek xénos = foreign and Latin transplantatio = transplantation). Great hopes are pinned on it, as there is a severe shortage of donor organs worldwide. In Germany alone, there are currently around 8500 people on the waiting list for a donor organ; most of them need a kidney. In contrast, there were only 870 donors in 2022. Many patients die because they do not receive a donor organ in time. Genetically modified body parts from animals are intended to help alleviate the shortage.
Xenotransplantation comes with risks, however. Normally, the human organism rejects implanted foreign organs, which must be prevented by genetic engineering interventions in the animals' genetic material. There is also a risk of transmitting pathogens from the animals to the patients. During the two-month observation period, the 58-year-old now being treated developed previously unknown, progressive defence reactions that made it necessary to administer increasing doses of immunosuppressive drugs. The doctors hope to be able to prevent this in future xenotransplantations.
Spectrum of Science
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Cover image: © Joe Carrotta / NYU Langone Health (detail) In July 2023, New York University surgeon Robert Montgomery and his team implanted a genetically modified pig kidney into a 58-year-old brain-dead patient.
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