Evaluation of Small Interfering RNA Delivery into Cells by Reverse Transfection in Suspension with Cationic Liposomes

Successful gene silencing by small interfering RNA (siRNA) requires efficient uptake of siRNA into targeted cells. For in vitro transfection of siRNA using cationic liposomes, two types of transfection method are currently being used: conventional (forward; Fw) and reverse (Rev) transfections. Here, to investigate an efficient siRNA transfection method using cationic liposomes, we compared the transfection efficiency of siRNA between Fw-transfection and Rev-transfection methods with various types of cationic liposomes. In Fw-transfection, siRNA/cationic liposomes complex (siRNA lipoplexes) was added to pre-plated cells. In contrast, Rev-transfection was performed by co-incubation of cells with siRNA lipoplexes in suspension. As a result, Rev-transfection with 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based or cationic cholesterol derivative-based liposomes could deliver siRNA into the cells via efficient cellular association, and induce an improved gene silencing effect by siRNA compared with Fw-transfection. Furthermore, Rev-transfection did not show increased cytotoxicity compared with Fw-transfection. These findings suggested that Rev-transfection in suspension has better potential for efficient transfection of siRNA into cells with minimal toxicity.