Lipid-coated polyplexes for targeted gene delivery to ovarian carcinoma cells

A nonviral gene delivery vector has been developed in our laboratory based on the cationic polymer, poly(2-(dimethylethylamino)ethyl methacrylate) (p(DMAEMA)). p(DMAEMA)-based polyplexes have been successfully used for the transfection of OVCAR-3 cells in vitro. However, these polyplexes were unable to transfect OVCAR-3 cells growing in the peritoneal cavity of nude mice after intraperitoneal administration, which could be ascribed to inactivation by components (including hyaluronic acid) present in the tumor ascitic fluid. The present work aimed at (a) protecting p(DMAEMA)-based polyplexes against destabilization or inactivation by polyanions such as hyaluronic acid present in tumor ascitic fluid and (b) enhancing cellular uptake of the protected p(DMAEMA)-based polyplexes by targeting with antibody Fab' fragments. To fulfill these requirements, we have developed a detergent removal method to coat polyplexes with anionic lipids. With this method, spherical particles of approximately 125 nm, which were protected from destabilization by polyanions, were obtained. More importantly, the transfection efficiency of lipopolyplexes was unaffected in the presence of hyaluronic acid, indicating that lipid coating of polyplexes protects against destabilization by hyaluronic acid. By conjugating antibody Fab' fragments directed against the epithelial glycoprotein-2 to the lipidic surface of these lipopolyplexes, target cell-specific transfection of OVCAR-3 cells could be obtained in vitro.