Taking polycation gene delivery systems from in vitro to in vivo.

It is widely believed that non-viral gene delivery systems may improve safety and overcome tissue-tropism limitations associated with viral-based gene therapies. Cationic liposome-based gene delivery currently accounts for 9-12% of ongoing gene therapy clinical trials in the United States and Europe. Polycation-based gene delivery is at an earlier development stage. However, both in vitro and in vivo studies have demonstrated that this is an area of much promise. Complexes of polycations with DNA result in major improvements in the control of size, charge, and the hydrophilic-lipophilic characteristics of the transfecting species, when compared with other non-viral systems. This review serves as an introduction to the current status of this field.