Gene-delivery systems using cationic polymers

Gene therapy will benefit a range of diseases from single-gene defects, to chronic diseases such as cancer, to vaccination. Initially, gene therapy used viral vectors, but the advantages of nonviral systems are now being fully appreciated. This review focuses on cationic polymers as a delivery system for DNA. The physicochemical characterization of DNA polycation complexes that condense and protect DNA from nuclease digestion are considered, together with further factors such as ligand targeting, endosomal escape, and nuclear localization. Where possible, the relative efficacy of different cationic polymer delivery systems is compared.