Boston, MA — (Jan 8th 2025)— Ourt team at Massachusetts General Hospital have published the first comprehensive immune analysis of a gene-edited pig kidney transplanted into a living human, providing critical insights into how the human immune system responds to xenotransplantation and identifying key challenges that must be addressed to advance the field.
The study, published in Nature Medicine, used high-dimensional transcriptomic, proteomic, metabolomic, and spatial imaging approaches to track immune responses before, during, and after transplantation. The findings show that while standard immunosuppressive therapies effectively controlled adaptive immune responses, innate immune activation persisted, revealing an important distinction between xenotransplantation and conventional human kidney transplantation.
Despite profound depletion of circulating T cells, the recipient developed an early episode of T cell–mediated rejection within the first week after transplant. This rejection was successfully reversed with intensified immunosuppressive therapy. However, researchers observed sustained activation of monocytes and macrophages, along with elevated inflammatory cytokines such as IL-1β and GM-CSF, highlighting unresolved innate immune pathways.
Importantly, the immune signatures observed in the pig kidney closely overlapped with those seen in human kidney transplant rejection, demonstrating conserved mechanisms of rejection. At the same time, xenograft-specific innate immune signals were identified, underscoring the need for tailored approaches in xenotransplantation. The study also showed that pig donor-derived cell-free DNA rose during rejection and declined after treatment, supporting its potential as a non-invasive biomarker for monitoring xenograft injury.
“Xenotransplantation has advanced at an extraordinary pace, bringing us closer than ever to a viable solution to the organ shortage,” said Leonardo V. Riella, MD, PhD, senior author of the study and Director of Kidney Transplantation Research at Massachusetts General Hospital. “While many aspects of the immune response to pig kidneys closely resemble what we see in human transplantation, our study reveals important differences, particularly the persistence of innate immune activation. Addressing these unresolved pathways will be critical to achieving durable graft survival and improving outcomes in xenotransplantation.”
The findings provide a roadmap for future strategies, including innate-targeted immunotherapies and next-generation genetic modifications in donor pigs designed to dampen inflammatory signaling. Together, these advances could help transform xenotransplantation into a scalable and durable alternative for patients with end-stage kidney disease who face long waiting times or limited access to human donor organs.
This work builds on Massachusetts General Hospital’s leadership in clinical xenotransplantation and informs ongoing and future trials aimed at expanding access to life-saving kidney transplants.
For patients interested in learning more about or participating in ongoing xenotransplantation clinical studies at MGH, visit: https://www.mghxenotransplant.org/