The use of transgenic animals for xenotransplantation: An update

Xenotransplantation, that is, the transplantation of cells, tissues, and organs between species, is a rapidly developing alternative to classical transplantology in human medicine. Since the first successful kidney transplant in 1954, transplant medicine has made enormous progress. Until today, there are numerous patients worldwide waiting for an organ to be transplanted, and the number is still increasing, whereas the number of available organs is decreasing. One promising solution to this critical issue is the breeding of genetically modified animals as potential donors, which has gained the attention of scientists over the past two decades. Recent advancements in xenotransplantation have led to successful transfers of genetically modified pig organs into human recipients. Particularly, pig kidneys have been transplanted into living humans, demonstrating normal postsurgical function. Additionally, pig lungs functioned for 9 days in a brain-dead individual without experiencing hyperacute rejection. Furthermore, the successful xenotransplantation of pig hearts into living persons, exhibiting life-sustaining graft function, underscores significant progress toward clinically viable xenotransplants. This review provides an updated overview of the animal species and models used in xenotransplantation, with particular emphasis on the potential of transgenic pigs as donors. It discusses the process involved in producing the aforementioned animals, including the methods used to modify their genome. Particular attention is paid to immunological and genetic barriers, as well as zoonotic risks, and the possibilities and limitations of this technology. Although xenotransplantation is still in its experimental stage, it may play a crucial role in saving patients' lives in the future.