Abstract
Recently, we developed polyethyleneglycol (PEG)-modified liposomes (Bubble liposomes; BLs) entrapping ultrasound (US) gas and reported that the combination of BLs and US exposure was an effective tool for the delivery of siRNA directly into cells and US-exposed tissues within a short period; however, the results were obtained using a mixture of BLs and naked siRNA. With systemic injections, it is important to control the biodistribution of both BLs and siRNA. In addition, the delivery of siRNA is affected by nuclease degradation and rapid removal from the circulation after intravenous administration. In this study, we attempted to prepare novel siRNA-loaded BLs (chol-si-BLs) using cholesterol-conjugated siRNA (chol-siRNA). We demonstrated that chol-siRNA could be loaded into BLs, leading to the stability of siRNA even in the presence of an RNase. The specific gene-silencing effect was also achieved by transfection with chol-si-BLs and US. Thus, the combination of chol-si-BLs with US exposure is expected to deliver siRNA into a specific tissue via systemic injection.
Acknowledgements
The authors are grateful to Prof. Katsuro Tachibana (Department of Anatomy, School of Medicine, Fukuoka University) for technical advice regarding the induction of cavitation with US, and to Mr. Yasuhiko Hayakawa and Mr. Kosho Suzuki (NEPA GENE Co., Ltd.) for technical advice regarding US exposure.
Declaration of interest
This study was supported by a Grant for Industrial Technology Research (04A05010) from the New Energy and Industrial Technology Development Organization (NEDO) of Japan, a Grant-in-aid for Scientific Research (B) (20300179) from the Japan Society for the Promotion of Science, a Grant-in-aid for Scientific Research (B) (19300185) from the Japan Society for the Promotion of Science, and a Grant-in-aid for Young Scientists (B) (21790164) from the Japan Society for the Promotion of Science. Kazuo Maruyama acknowledges the Program for Promotion of Fundamental Studies (Project ID: 10–23) in Health Sciences of the National Institute of Biomedical Innovation (NIBIO).