Engineered neuronal exosomes mediate α-synuclein clearance to ameliorate Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. A hallmark pathological feature of PD is the abnormal aggregation of α-synuclein (αSyn) into insoluble Lewy bodies. Consequently, developing strategies to inhibit αSyn aggregation in the brain has been a major research focus for PD treatment. This study developed a therapeutic approach using engineered neuronal exosomes. These exosomes were modified to extend their blood circulation half-life to 3.8 h and enhance targeting, with a 2.15 ± 0.09% brain signal proportion (vs. 0.78 ± 0.07% for free dye). They were then loaded with a self-developed αSyn aggregation-blocking peptide (sPep) as well as the antioxidant pyrroloquinoline quinone (PQQ). We investigated the therapeutic efficacy of this system in both in vitro and in vivo models of PD. Our experiments confirmed that the screened sPep effectively targeted and blocked αSyn aggregation both in vitro and in vivo. Neuronal exosomes, isolated by ultracentrifugation and hybridization, demonstrated strong abilities to cross the blood-brain barrier. In vivo studies revealed that the treatment significantly improved motor and cognitive functions in PD model mice. The underlying neuroprotective mechanisms included reducing αSyn aggregation, enhancing antioxidant capacity, ameliorating mitochondrial dysfunction, and suppressing cell apoptosis, collectively promoting the survival of dopaminergic neurons. These findings demonstrate that the engineered exosome-mediated delivery system exerts a protective effect against PD pathology.