Targeted gene delivery to human osteosarcoma cells with magnetic cationic liposomes under a magnetic field.

Gene delivery using cationic liposomes results in relatively low transfection, especially under in vivo conditions. This system, however, can overcome some of the problems associated with viral delivery systems. The present study was carried out in order to improve the transfection efficiency of cationic liposomes by preparing magnetic cationic liposomes (MCL). Small MCL approximately 40 nm in diameter and incorporating one or two magnetite particles were prepared with phosphatidylethanolamine and 3beta-[N-(N', N'-dimethylaminoethane)-carbamoyl] cholesterol. The efficiency of MCL in gene delivery was evaluated by using plasmid DNA containing a luciferase reporter gene and human osteosarcoma Saos-2 cells. Without a magnetic field, maximum luciferase activity was observed when DNA was mixed with MCL at a 1:5 ratio and incubated with cells for 6 h. Under a magnetic field, maximum luciferase activity was achieved by 30-min magnetic induction. This improvement in transfection efficiency by magnetic induction was approximately 3.5-fold. The feasibility of this active transgenic system was further shown by measuring apoptosis rates after transfection of the p53 gene to Saos-2 cells. Apoptosis rates increased to 18.9% from 2.4% by magnetic induction. In conclusion, a gene delivery system including MCL and magnetic induction was found to achieve rapid and enhanced gene delivery in vitro. Such a gene delivery system may be applicable under in vivo conditions, and is expected to offer numerous clinical advantages.