Mitochondria-enriched BMSC exosomes restore microglia-neuron cross-talk in Parkinson's disease via PINK1/parkin and PI3K/Akt/mTOR pathways.

BACKGROUND: Mitochondrial dysfunction and neuroinflammation drive dopaminergic neuron loss in Parkinson's disease (PD). While BMSC-derived small extracellular vesicles (BMSC-Exo) are neuroprotective, their ability to repair mitochondrial deficits is limited. We engineered mitochondrial-enriched sEVs (Exo-Mito) to evaluate their effects on microglia-neuron interactions in a PD-relevant model.

METHODS: BMSC-Exo-Mito were characterized via TEM, NTA, and immunoblotting. Their therapeutic efficacy was assessed using an MPP + -induced BV2/SH-SY5Y transwell co-culture model. Assessments included ROS levels, mitochondrial membrane potential, ATP quantification, mitophagy flux, and signaling pathway analysis.

RESULTS: Exo-Mito significantly restored mitochondrial homeostasis by reducing ROS, preserving membrane potential, and increasing ATP production. Mechanistically, Exo-Mito enhanced PINK1/Parkin-dependent mitophagy and PGC-1alpha/TFAM-mediated biogenesis. In BV2 microglia, Exo-Mito suppressed the NF-kappaB/NLRP3 axis, reduced proinflammatory cytokines, and promoted M2 polarization. In SH-SY5Y cells with dopaminergic phenotype, Exo-Mito was associated with reactivated PI3K/Akt/mTOR signaling, preserved tyrosine hydroxylase expression, and inhibited apoptosis. Functionally, Exo-Mito improved SH-SY5Y cell and restored microglial migratory capacity, showing superior efficacy to unmodified BMSC-Exo.

CONCLUSION: Mitochondria-enriched BMSC sEVs protect SH-SY5Y cells by coordinating mitochondrial quality control and modulating neuroinflammation. These findings support Exo-Mito as a promising cell-free therapeutic strategy for Parkinson's disease.