Functional Xenogeneic Liver Support in a Living Human: Promise, Lessons, and Next Steps.

Genetically engineered porcine organs are redefining the boundaries of clinical xenotransplantation. Zhang et al. now report the first functional pig-to-human liver xenotransplantation in a living patient, demonstrating that a 10-gene-edited auxiliary porcine liver can engraft, produce bile, and synthesize metabolic and coagulation factors in vivo. The xenograft supported a high-risk hepatectomy with borderline remnant volume and contributed to early postoperative stability, although xenotransplant-associated thrombotic microangiopathy ultimately required graft removal. The case highlights both the promise of xenogeneic hepatic support and the physiologic limits that currently preclude durable therapy, including thrombocytopenia, complement-coagulation incompatibility, portal-flow competition, and challenges in assessing dual-graft function. These results establish proof-of-concept for temporary porcine liver support in humans and outline key priorities for next-generation designs: optimized thromboregulation, mitigation of xTMA, improved immunomodulation, and strategies for controlled transition to native-liver autonomy.