Current Progress in Kidney Xenotransplantation: Time to Proceed to Clinical Trials

Kidney transplantation is the ideal treatment for end-stage kidney disease, but the shortage of donors limits its clinical implementation. Although xenotransplantation, particularly from pigs, is a promising approach to address the donor shortage, significant challenges, such as immune rejection and disease transmission, exist. However, recent advances in gene-editing technology as well as development of novel immunosuppressive drugs have significantly improved xenotransplant outcomes in nonhuman primates. Recent studies on xenotransplantation using decedent recipients have provided novel insights into human immune responses to porcine xenografts, despite the limited observation time in these recipients. Building upon these preclinical studies, four cases of clinical kidney xenotransplantation have recently been performed under a "expanded access authorization." Understanding immunological responses, as well as various physiological discrepancies between human and porcine kidney function, must be enhanced before xenotransplantation can become a viable clinical solution to organ shortages. This review summarizes the current progress of kidney xenotransplantation in nonhuman primate models, decedent models, and clinical cases.