Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra and the pathological aggregation of α-synuclein (α-syn) into Lewy bodies and it is known as the second most prevalent neurodegenerative disorder. The pathogenesis of PD involves mitochondrial dysfunction, oxidative stress, impaired protein degradation, and neuroinflammation. Current therapeutic strategies are largely symptomatic and remain limited in their ability to halt disease progression. Resveratrol (Res) has been shown to mitigate oxidative stress, preserve mitochondrial integrity, and reduce α-syn aggregation in PD models due to its antioxidant and neuroprotective properties. Despite its promising therapeutic potential, its poor bioavailability and rapid metabolism hinder the achievement of the desired therapeutic effects, which calls for advanced drug delivery systems. Human umbilical cord-derived mesenchymal stem cell (hUC-MSC) exosomes (Exos) are nanoscale extracellular vesicles with intrinsic neuroprotective, anti-inflammatory, and regenerative properties. They represent a promising carrier system owing to biocompatibility and the ability to cross the blood-brain barrier. Since the isolation technique is a critical parameter affecting both Exos yield and therapeutic efficacy, the study initially focused on optimizing the isolation process through a comparative investigation of ultracentrifugation and commercial isolation kits. Exos obtained with the highest yield and optimal characteristics, were subsequently subjected to Res loading through the probe sonication method. After the physicochemical characterization of Res-loaded exosomes (Exo-Res), their therapeutic potential was evaluated in an in vitro PD model established by rotenone-induced neurotoxicity in SH-SY5Y cells. Cell viability, oxidative stress, mitochondrial function, and whole protein aggregation were comprehensively assessed. Exo-Res isolated with Kit-1 showed a smaller particle size (94.0 nm) with high homogeneity (PDI < 0.3), high yield (3.9 × 1011 particles/mL), and good entrapment efficiency (58.3%). It released Res in a sustained manner over 4 h. Our findings confirmed that Exo-Res significantly reduced whole protein aggregation mitigated oxidative stress, enhanced neuronal survival, and preserved mitochondrial function more effectively than either free Res or unloaded Exos. These results show that Exo-Res is a promising biocompatible nanocarrier-based therapeutic strategy for PD and possibly other neurodegenerative disorders, overcoming the key challenge of Res bioavailability while benefiting from the biocompatibility and therapeutic performance of exosomes.
