Small interfering RNA (siRNA) molecules have been successfully used to target specific genes in cell culture. However, the lack of specificity for siRNA to cells and lack of permeability to the blood brain barrier has humbled their use as therapeutic agents especially for neurodegenerative diseases. Recently, we have designed non-viral vectors that can specifically deliver functional siRNA into cultured neuronal cells. The objective of our proposal is to carry out a detailed study to test the potential use of our vectors in pre-clinical models, and to determine the efficacy of our vectors to deliver functional siRNA targeting the brain.
We will first investigate the toxicity of vectors complexed with siRNA in normal pre-clinical models. Acute toxicity of the intravenously injected complexes will be tested in young and adult pre-clinical models. After optimizing the toxicity for our complexes, we will then test whether our lead peptides can transport specifically siRNA into brain cells.
We will then assess the ability of our non-viral vectors to silence specifically genes in the brain that are related to Parkinson’s disease such as alpha-synuclein gene.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
Recent genetic and pre-clinical model studies of Parkinson’s disease have indicated that increased expression of the wild-type alpha-synuclein protein enhances the risk of developing Parkinson’s disease. Thus, silencing of wild-type alpha-synuclein gene is considered to be a promising therapeutic approach for treating Parkinson’s disease.
If we obtain positive results using our non-viral vectors that indicate a successful delivery of siRNA targeting brain, then our study opens a new avenue for the development of an efficient and safe siRNA delivery system for therapeutic applications targeting CNS diseases such as Parkinson’s disease.
Recent genetic and animal model studies of Parkinson’s disease have indicated that increased expression of alpha-synuclein gene enhances the risk of developing Parkinson’s disease. Thus, silencing this gene is considered to be a promising therapeutic approach for treating Parkinson’s disease.
Gene expression can be specifically modulated by molecules named small interfering RNAs (siRNAs). Although siRNAs have emerged as a powerful tool for modulating gene expression and a potential therapeutic strategy to silence disease-causing genes, delivery of siRNA into neurons remains a major challenge. The brain is particularly challenging because of the heterogeneity of cell types, volumetric constraints, and the presence of the blood-brain barrier. Recently, we have designed non-viral vectors that can deliver functional small interfering siRNAs specifically into cultured neuronal cells. The objective of our proposal was to carry out a detailed study to test the potential use of our vectors in mice, and to determine the efficacy of our vectors to deliver functional siRNA targeting the brain. Our results clearly demonstrated that our non-viral vectors have the ability to cross the blood-brain barrier and able to target specifically the brain. We observed no sign of abnormal morphology and cellular toxicity in the liver, kidney or brain sections collected from treated mice with our victors.
To test brain-tissue specific gene silencing, normal mice were injected intravenously with siRNA molecules designed specifically to target alpha-synuclein gene after complexed with our non-viral victors. We found significant decrease in alpha-synuclein gene expression in different brain regions after treatment. Taken together, our results show that our non-viral vectors able to deliver the siRNA targeting the brain and suppress specifically the Parkinson’s diseases related gene.