AAV-mediated FGF21 gene therapy promotes health span extension by whole-body tissue-specific adaptations.

The decline of organ function during aging limits health span. Despite the potential of lifestyle interventions to improve health, sustained maintenance of health span is challenging, and no gerotherapeutic drugs have been approved. Here, we demonstrated that aged and geriatric male and female mice treated with muscle-directed adeno-associated viral (AAV) vector-mediated fibroblast growth factor 21 (FGF21) gene therapy extended health span and lifespan with sustained organ benefits. This treatment normalized body weight and adiposity, improved insulin sensitivity and glucose homeostasis, preserved hepatic detoxification capacity, counteracted age-related kidney disease, promoted cardiac health and muscular function, and enhanced cognition. Transcriptomic and histopathological analyses indicated improved whole-body energy homeostasis and cellular fitness, which were mediated by tissue-specific adaptations, including enhanced mitochondrial function, restored proteostasis, and reversion of inflammation, fibrosis, and amyloidosis. AAV-FGF21 treatment also activated AMPK signaling. These results highlight FGF21 gene therapy as a potential strategy to promote health span and delay age-related deterioration.