Targeted nanovesicular delivery of dexmedetomidine modulates microglial lysosomal function via Sirt3 signaling to ameliorate neurodegenerative pathology.
Neuroinflammation and lysosomal dysfunction in microglia are increasingly recognized as critical pathological drivers of Alzheimer's disease, yet current anti-inflammatory or neuroprotective agents have limited brain delivery efficiency and cellular specificity. To address these challenges, this study proposes a novel nanotherapeutic paradigm based on extracellular nanovesicles (ENVs) for targeted modulation of microglial function. This research explored the potential of a novel nanotherapeutic platform involving ENVs functionalized with aptamers and encapsulating dexmedetomidine (Dex) to alleviate microglia-associated neuroinflammation in Alzheimer's disease. The effects on microglial lysosomal function, neuroinflammation, and cognitive performance were evaluated in an Alzheimer's disease mouse model. Cholesterol-conjugated PEG 2000 aptamers were used to modify extracellular nanovesicles derived from microglial cells. The nanovesicles (ZH-1c-ENVs) were loaded with Dex using ultrasound-assisted methods. Particle size, morphology, and drug release kinetics were characterized using dynamic light scattering and transmission electron microscopy. In vitro assays assessed microglial cell uptake and cytotoxicity, while in vivo biodistribution was evaluated in a mouse model. Proteomics, western blotting, quantitative reverse transcription-polymerase chain reaction, and immunofluorescence were employed to analyze the effects of ZH-1c-ENVs@Dex on microglial inflammation, lysosomal activity, and amyloid-beta clearance. Cognitive function improvements were assessed using the Morris water maze. ZH-1c-ENVs@Dex achieved efficient drug encapsulation and crossed the blood-brain barrier, delivering Dex selectively to microglial cells. Proteomic analysis revealed activation of the Sirtuin 3 signaling pathway, which reduced microglial inflammation and enhanced lysosomal function. These changes promoted amyloid-beta clearance in vitro and alleviated neuroinflammation in vivo. Treatment significantly improved cognitive performance in Alzheimer's disease mice. The ZH-1c-ENVs@Dex system represents a promising nanomedicine strategy for Alzheimer's disease therapy by modulating Sirtuin 3 activity, restoring microglial function, and improving cognitive outcomes. This study lays the groundwork for clinical translation of aptamer-modified ENVs as precision nanomedicines for neurodegenerative diseases. The ZH-1c-ENVs@Dex system integrates clinically safe components, efficiently traverses the blood-brain barrier, and selectively targets microglia, exhibiting remarkable potential for the treatment of Alzheimer's disease and related neurodegenerative disorders. This scalable and highly biocompatible nanovesicular platform offers a clinically translatable strategy with substantial therapeutic promise for neuroinflammatory and neurodegenerative diseases.