Abstract
AIMS: Gene therapy targeting the SNCA gene yields promising results in the treatment of Parkinson's disease (PD). The most challenging issue of the RNAi gene therapy strategy is maintaining efficient delivery without inducing significant toxicity and other adverse effects. This study aimed to characterize polyethylene glycol-polyethyleneimine as a vector for alpha-synuclein siRNA delivery to PC12 cells for Parkinson's disease. METHODS: The characteristics of PEG-PEI/siSNCA were analyzed via gel retardation assay and assessments of particle size and zeta potential. MTT cytotoxicity assay and flow cytometry were used to detect cytotoxicity and transfection efficiency in PC12 cells. Confocal laser scanning microscopy was employed to examine the intracellular distribution of PEG-PEI/FITC-siSNCA after cellular uptake. RT-PCR and western blotting were used to measure SNCA expression. The MTT cytotoxicity assay was used to study the effect of PEG-PEI/siSNCA on cell viability. The protective effect of PEG-PEI/siSNCA on MPP+-induced apoptosis in PC12 cells was examined via flow cytometry and Hoechst staining. RESULTS: PEG-PEI/siSNCA complexes were well-developed; they exhibited appropriate particle sizes and zeta potentials at a mass ratio of 5:1. In vitro, PEG-PEI/siSNCA was associated with low cytotoxicity and high transfection efficiency. Complexes were capable of successfully delivering siSNCA into PC12 cells and releasing it from the endosome. Furthermore, PEG-PEI/siSNCA could effectively suppress SNCA mRNA expression and protected cells from death via apoptosis induced by MPP(+) . CONCLUSIONS: Our results demonstrate that PEG-PEI performs well as a vector for alpha-synuclein siRNA delivery into PC12 cells. Additionally, PEG-PEI/siSNCA complexes were suggested to be able to protect cells from death via apoptosis induced by MPP(+) . These findings suggest that PEG-PEI/siSNCA nanoparticles exhibit remarkable potential as a gene delivery system for Parkinson's disease.