Intranasal L-DOPA/TPP-engineered extracellular vesicles deliver icariin to ameliorate mitochondrial dysfunction with...

Alzheimer's disease (AD) is associated with mitochondrial dysfunction, oxidative stress, and disrupted lipid homeostasis, but the therapeutic translation of mitochondrial-protective agents remains limited by inefficient brain delivery, insufficient neuronal selectivity, and poor subcellular precision. Here, we developed an intranasal extracellular vesicle formulation (L-DOPA/TPP-EV-ICA) by loading icariin (ICA) into mesenchymal stem cell-derived extracellular vesicles and post-inserting DSPE-PEG-Levodopa and TPP-PEG-PE to enhance nasal environment, neuronal association, and mitochondria-associated intracellular enrichment. The engineered vesicles retained EV-like morphology, showed measurable ICA encapsulation, and maintained colloidal stability under the tested storage and simulated nasal conditions. In a human nasal epithelial Transwell model, L-DOPA/TPP-EV-ICA showed greater neuronal uptake than unmodified EVs without detectable disruption of epithelial barrier integrity and exhibited preferential colocalization with mitochondria-associated structures after cellular internalization. In Aβ-injured neuronal cells, L-DOPA/TPP-EV-ICA treatment reduced mitochondrial oxidative stress and mPTP opening, improved membrane potential, and enhanced ATP production and redox-related parameters. Following intranasal administration, the engineered formulation generated stronger and more persistent brain-associated fluorescence and showed preferential association with NeuN-positive cells. In APP/PS1 mice, treatment improved cognitive performance, and attenuated histopathological and mitochondrial abnormalities. Integrated proteomic, metabolomic analyses, and protein-level analyses further identified treatment-associated alterations in sphingolipid-related pathways. These findings support L-DOPA/TPP-EV-ICA as a promising preclinical intranasal EV platform for improving mitochondrial function and modulating sphingolipid-associated alterations in AD-related models.