Assessment of a modular transfection system based upon cellular localization of DNA

Delivery of plasmid DNA for protein production in mammalian cells is not an efficient process. In this study, the theory that cellular localization of plasmid DNA increases transfection efficiency is examined with an emphasis on the understanding of the cellular association of the components of a ternary transfection complex. Mammalian cells take up transfection reagent-DNA complexes primarily from their local environment. Via formation of a ternary complex consisting of the DNA-transfection reagent complex and a heavy particle, such as silica, the efficiency of transfection is substantially increased. We have analyzed cells transfected with the ternary complexes to determine if sedimentation alone affects the percentage of cells that contain the complexes or specific components of the complex. A significant fraction of cells associate with the ternary complexes, including silica nanoparticles. The percentage of cells that associate with DNA was not significantly influenced by the use of the ternary complex. This result suggests that the silica nanoparticles are more than just a sedimentation agent, being also a secondary transfection reagent. These data also confirm that cells may contain transfection reagent-DNA complex but do not express the protein of interest. This knowledge will be used in further research to better design transfection reagents that will increase the efficiency of protein production.