Experimental Research Article : The optimal concentration of siRNA for gene silencing in primary cultured astrocytes and microglial cells of rats

Background: Small interfering RNAs (siRNAs) have been used to knockdown specific gene expression in various cells. Astrocytes and microglial cells play a key role in fundamental central nervous system functions and in chronic neuroinflammation. The aims of this study were to determine the optimal concentration of siRNA demonstrating efficient transfection and inhibition of gene expression via RNA interference (RNAi) and lower cytotoxicity, in primary cultured astrocytes and microglial cells of rats. Methods: Astrocytes and microglial cells were isolated from the cerebral cortices of 2-day-old rats. Both the cells were transfected using transfection reagent (LipofectamineTM 2000), and fluorescein-labeled double-stranded RNA (dsRNA) or siRNA targeting green fluorescent protein. Transfection efficiency and cytotoxicity of dsRNA, and the degrees of RNAi induced by siRNA in these cells, were evaluated at various concentrations of RNA. Results: Transfection efficiencies of dsRNA in both astrocytes and microglial cells were significantly higher (P