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. A hierarchical strategy is engineered to interrupt the vicious crosstalk in pulmonary fibrosis. By utilizing rejuvenated alveolar epithelial cells II as biomanufacturing factories, reparative exosomes are harvested to encapsulated healthy mitochondria. The mannose-functionalized “Exosome-Ark” targets macrophages and provides a cytoplasm-like protective milieu, effectively restoring metabolic homeostasis and suppressing fibrotic progression through synergistic organelle replacement and immunomodulation.
Zhang et al. (Fri,) studied this question.