# Xeno kidney: revolutionizing kidney disease treatment

## TL;DR

Xenotransplantation, using pig kidneys, offers a potential solution to the shortage of human donor organs for kidney transplants, despite challenges like immune rejection.

## Contribution

The paper highlights recent advances in xenotransplantation, including genetic engineering and immunosuppressive strategies, to improve the viability of pig kidney transplants.

## Key findings

- Genetic modifications like GalTKO in donor pigs reduce immunogenicity and complement activation.
- Immunosuppressive regimens such as co-stimulation blockade and anti-complement treatment show promise for xenograft acceptance.
- Strategies like mixed chimerism and regulatory T-cell therapy aim to induce tolerance without lifelong immunosuppression.

## Abstract

The prevalence of end-stage kidney failure has been exponentially increasing, leading to a gross mismatch between the number of patients who may benefit from transplantation and the limited supply of suitable donor organs. As renal transplantation remains a viable and the most effective option for end-stage kidney disease, the fact remains that the availability of eligible human donor organs is highly unlikely to meet the projected demand. This undermines the need for alternative strategies, including therapies and the development of transplant substitutes. In this context, xenotransplantation has emerged as a lucrative avenue for patients with renal failure who struggle to obtain a suitable graft promptly. The pig is currently the most preferred animal donor for kidney due to its physiological analogy to humans. Nevertheless, xenotransplantation is associated with certain complications as well, which broadly include the risk of hyperacute rejection mediated by preexisting antibodies to xenogeneic antigens, the stimulation of innate immune responses, and thereby the possibility of chronic rejection. Recent advances in xenotransplantation research have offered hope in overcoming these roadblocks and transforming the field of nephrology in the coming years. Genetic engineering has enabled creating low-immunogenicity grafts from donor pigs, including GalTKO (lacking α-Gal epitopes/galactose-α-1,3-galactose knockout) and gene knockouts that limit the complement system activation and clot formation. Furthermore, advances in immunosuppressive regimens, such as co-stimulation blockade and anti-complement treatment, hold great promise for xenograft acceptance and long-term results. In addition, numerous strategies are being explored to induce tolerance, such as mixed chimerism or regulatory T-cell therapy, to achieve a condition of acceptable graft tolerance without dependency on lifelong immunosuppressive treatments. Collectively, these developments support the translational potential of xenotransplantation as a stand-alone treatment or as an adjunct to standard renal replacement therapies. Despite the setbacks, ongoing preclinical research and early clinical trials are expected to refine the safety, durability, and clinical applicability in a xenotransplantation setting.

Infographic compares kidney allotransplantation and xenotransplantation, highlighting organ shortage and complications such as graft rejection, surgery risk, and zoonotic diseases, and depicts future directions including genetic modifications, immunosuppressive strategies, bio-printing, and ethical considerations.