Targeting the LRRK2 G2019S Mutation Found in Parkinson's Disease: Efficiency of Biosynthesized Solid Lipid Nanoparticles for Therapeutic siRNA-Mediated Gene Therapy.

BACKGROUND: Parkinson's disease (PD) is a progressive neurodegenerative disorder with which the leucine-Rich repeat kinase 2 glycine 2019 serine (LRRK2 G2019S) mutation is strongly associated. This mutation elevates kinase activity, disrupts mitochondrial function, increases reactive oxygen species (ROS) production, and impairs DNA repair mechanisms, all of which contribute to the pathogenesis of PD. Thus, addressing these pathological features through targeted delivery systems holds promise for more effective therapies.

METHODS: This study aimed to investigate the use of Ginkgo biloba leaf extract (EGB) to synthesize sphingomyelin-cholesterol solid lipid nanoparticles (SLNPs) functionalized with poly-L-lysine (EGB-PLL-SLNPs) for siRNA delivery targeting the LRRK2 G2019S mutation. SLNPs suspended in water (H₂O-PLL-SLNPs) served as the comparator. In vitro assays were conducted using either wild-type or LRRK2 G2019S-transformed SH-SY5Y and HEK293 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was employed to evaluate the cytotoxicity of the SLNPs and nanocomplexes; meanwhile, flow cytometry was used to assess caspase 3/7 activity, mitochondrial membrane potential, DNA damage, and ROS levels.

RESULTS: Treatment with EGB-PLL-SLNPs significantly improved mitochondrial health, reducing depolarized and dead cells and enhancing overall cell viability. ROS levels, DNA damage and kinase activity were significantly decreased compared to the control H₂O-PLL-SLNPs.

CONCLUSION: The enhanced therapeutic outcomes observed with the EGB-PLL-SLNPs can be attributed to the bioactive compounds in EGB, particularly the flavonoids and terpenoids, such as quercetin and kaempferol. These molecules play crucial roles in stabilizing mitochondrial membranes, facilitating ATP synthesis, and regulating genes linked to mitochondrial biogenesis. The interaction between EGB and siRNA to mediate gene silencing provides a multifaceted approach to counteracting PD pathophysiology. This study demonstrates that EGB-PLL-SLNPs offer superior gene silencing and cytoprotective effects compared to conventional formulations. The integration of plant-based bioactives with nanomedicine enhances therapeutic delivery and efficacy, positioning biosynthesized PLL-SLNPs as a promising strategy for treating Parkinson's disease.