PGA-coated lipoplexes of 50 µg of ApoB siRNA-Chol were intravenously administered via lateral tail veins into mice. At 24 h post-injection, mice were fasted for 24 h. At 48 h post-injection, blood was collected from the carotid arteries of mice under anesthesia, and allowed to stand for 1 h at 37 °C. Serum low-density-lipoprotein (LDL) cholesterol level Buparlisib was measured using a commercial

LDL cholesterol detection kit according to the manufacturer’s instructions (HDL and LDL/VLDL Cholesterol Quantification Kit, Bio Vision Incorporated, Milpitas, CA, USA). Serum was prepared by separation of the coagulated whole blood of female C57BL/6Cr mice (7 weeks of age; Sankyo Lab. Service Corp., Tokyo, Japan) 24 h after intravenous injection of cationic and anionic polymer-coated lipoplexes of 50 µg of Cont siRNA-Chol. Aspartate aminotransferase (AST/GOT) and alanine aminotransferase (ALT/GPT) BMS754807 activities in the plasma were determined using commercially available test reagents (GPT-UV test Wako and GPT-UV test Wako, respectively; Wako, Osaka, Japan). Normal values were determined using blood obtained from age-matched, untreated mice. The statistical significance

of differences between mean values was determined by using Student’s t-test. A p value of 0.05 or less was considered significant. The cationic lipid, 1,2-dioleoyl-3-trimethylammonium propane (DOTAP), has frequently cAMP inhibitor been used as a cationic lipid for a liposomal delivery system of siRNA

by several research groups [[14], [15], [16] and [17]]. Among cationic liposomes, DOTAP/Chol liposome is commercially supplied as an in vivo transfection reagent (e.g., in vivo MegaFectin™ from Qbiogene Molecular Biology, in vivo Liposome Transfection Reagent from Sigma-Aldrich), which was demonstrated to have high transfection efficiency in the lungs by intravenous injection. Here, we selected chondroitin sulfate C (CS), poly-l-glutamic acid (PGA) and poly-aspartic acid (PAA) as materials for coating cationic DOTAP/Chol lipoplexes of siRNA and evaluated their potential for use as an siRNA delivery vector. First, we prepared DOTAP/Chol liposome and measured the particle size and ζ-potential. The liposome size was about 80 nm and the ζ-potential was +50 mV. When the liposomes were mixed with siRNA, the lipoplex size was about 280 nm and the ζ-potential was +40 mV. Next, we coated the lipoplexes with anionic polymers, CS, PGA and PAA, at various charge ratios (−/+), and prepared CS-, PGA- and PAA-coated lipoplexes. With increasing amounts of CS, PGA and PAA being added to the lipoplex, their sizes decreased to 150–200 nm and ζ-potential to a negative value (Fig. 1A–C). Although the sizes of CS-, PGA- and PAA-coated lipoplexes were smaller than that of cationic lipoplex, the anionic polymers may be able to strongly compact the cationic lipoplex by the electrostatic interaction.