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.