High efficacy gold-KDEL peptide-siRNA nanoconstruct-mediated transfection in C2C12 myoblasts and myotubes

Gold nanoparticles (AuNP) were conjugated with cysteine terminated KDEL (Lys-Asp-Glu-Leu) peptide and siRNA directed against NADPH Oxidase 4 (Nox4). Fluorescence microscopy analysis provided evidence of cytocellular retrograde transport pathways and sub-cellular colocalization of AuNP nanoconstructs in both undifferentiated C2C12 myoblasts and differentiated C2C12 myotubes. The cellular trafficking of AuNP nanoconstructs in undifferentiated myoblasts suggests stable and efficient transfection of siRNA as demonstrated by colocalization of AuNP-delivered KDEL and siRNA. The cellular uptake of AuNP nanoconstructs was more efficient than Lipofectamine mediated transfection in differentiated myotubes (P < 0.05) compared to undifferentiated myoblasts, suggesting that AuNP nanoconstructs provide an efficient platform for siRNA delivery to differentiated myotubes. The localization of these nanoconstructs in undifferentiated myoblasts suggests that most of the siRNA was localized in the endoplasmic reticulum (ER) with a minimal distribution in the Golgi bodies suggesting that the ER is a primary localization site for AuNP-KDEL mediated delivery of nanoconstructs. This team of investigators demonstrate that a delivery system composed of gold nanoparticle and KDEL based siRNA is superior to lipofectamine in delivering siRNA in differentiated myoblasts, paving the way to gene silencing methods in these cells for future therapeutic exploitation.