Perspectives on polymeric gene delivery

Research in the field of nonviral gene delivery is in the initial stages relative to the more commonly known viral systems. However, nonviral systems may, in the near future overcome some of the problems inherent to currently employed viral gene delivery systems. These problems range from limited payload capacity and general production issues to immune and toxic reactions, as well as the potential for catastrophic viral recombination. Self-assembling complexes of nucleic acids and synthetic polymers, commonly referred to as 'polyplexes', are formed as the result of electrostatic interactions between the negatively charged phosphate groups of the DNA and the positively charged groups of the polycation. A wide array of polycations are available for such studies, including those with linear, branched, dendritic and block or graft copolymer architectures. These polycations vary greatly in chemical composition as well as the number of repeating units, providing for a wide range of different polyplexes that can be easily assembled. Some of the current gene delivery systems are described which serve as potential reagents in the field of polymer-based gene delivery.