High-efficiency gene transfection of macrophages by lipoplexes

Macrophage transfection studies are crucial for understanding gene regulation and expression. However, gene transfection in macrophages is difficult. We have shown here that macrophages are more resistant to gene transfection compared with other cell types. To further develop an efficient gene delivery system for macrophages, we evaluated various liposomal and non-liposomal agents including LipofectAMINE®, Lipofectin®, DOTAP, DEAE-dextran, and the DNA condensing agent protamine sulfate for their ability to promote gene transfection. CMV-luciferase was used as a reporter plasmid. Macrophage transfection was maximal at the DNA:LipofectAMINE:protamine ratio of 1:12:1 μg/ml. The LipofectAMINE formulation showed a 10–12-fold increase in transfection efficiency over DOTAP and a 4–5-fold increase over Lipofectin. This transfection method showed minimal toxicity at the concentrations tested and was at least 20–25-fold superior to the most frequently used DEAE-dextran method for macrophage transfection.