Reparative "exosome-ark" for mitochondrial transplantation to reprogram macrophages and disrupt pathogenic crosstalk...

Pulmonary fibrosis (PF) progresses through a vicious cycle of crosstalk between injured alveolar epithelial cells II (AECs II) and alveolar macrophages. While mitochondrial transplantation offers a promising cure for macrophage metabolic dysfunction, the efficacy is hampered by poor targeting and rapid loss of mitochondrial integrity in vivo. Herein, we engineered a hierarchical strategy that integrates biomanufacturing, organelle protection and metabolic reprogramming. Initially, we utilized a "hijacking" strategy for manufacturing, where lipid nanoparticles (LNPs) delivering a mitochondrial-targeting sirtuin 3 plasmid (pMTS-SIRT3) rejuvenated injured AECs II, transforming them into factories for reparative exosomes. These harvested vesicles were then engineered into an "Exosome-Ark" by encapsulating healthy mitochondria. The pro-reparative intra-exosomal microenvironment functions as a cytoplasm-like milieu to maintain the biological activity of the isolated mitochondria, while mannose functionalization ensured macrophage-specific targeting. In bleomycin (BLM)-induced PF mice model, "exosomes-ark" restored macrophage mitochondrial homeostasis through enhanced fusion-fission dynamics and metabolic reprogramming, suppressed transforming growth factor-β (TGF-β) expression, and attenuated myofibroblast activation. Mechanistically, exosomal reparative signals promoted macrophages for mitochondrial engraftment, revealing a synergistic effect beyond simple organelle replacement. This study presented a biologically inspired platform, offering a translational potential for treating fibrotic diseases driven by AECs II-immune cell crosstalk.