@article{oai:nagasaki-u.repo.nii.ac.jp:00005726,
 author = {Kodama, Yukinobu and Shiokawa, Yumi and Nakamura, Tadahiro and Kurosaki, Tomoaki and Aki, Keisei and Nakagawa, Hiroo and Muro, Takahiro and Kitahara, Takashi and Higuchi, Norihide and Sasaki, Hitoshi},
 issue = {8},
 journal = {Biological and Pharmaceutical Bulletin},
 month = {Aug},
 note = {We developed a novel small interfering RNA (siRNA) delivery system using a ternary complex with polyethyleneimine (PEI) and γ-polyglutamic acid (γ-PGA), which showed silencing effect and no cytotoxicity. The binary complexes of siRNA with PEI were approximately 73-102 nm in particle size and 45-52 mV in a-potential. The silencing effect of siRNA/PEI complexes increased with an increase of PEI, and siRNA/PEI complexes with a charge ratio greater than 16 showed significant luciferase knockdown in a mouse colon carcinoma cell line regularly expressing luciferase (Colon26/Luc cells). However, strong cytotoxicity and blood agglutination were observed in the siRNA/Lipofectamine complex and siRNA/PEI16 complex. Recharging cationic complexes with an anionic compound was reported to be a promising method for overcoming these toxicities. We therefore prepared ternary complexes of siRNA with PEI (charge ratio 16) by the addition of γ-PGA to reduce cytotoxicity and deliver siRNA. As expected, the cytotoxicity of the ternary complexes decreased with an increase of γ-PGA content, which decreased the a-potential of the complexes. A strong silencing effect comparable to siRNA/Lipofectamine complex was discovered in ternary complexes including γ-PGA with an anionic surface charge. The high incorporation of ternary complexes into Colon26/Luc cells was confirmed with fluorescence microcopy. Having achieved knockdown of an exogenously transfected gene, the ability of the complex to mediate knockdown of an endogenous housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), was assessed in B16-F10 cells. The ternary complex (siRNA/PEI16/γ-PGA12 complex) exhibited a significant GAPDH knockdown effect. Thus, we developed a useful siRNA delivery system., Biological and Pharmaceutical Bulletin, 37(8), pp.1274-1281; 2014},
 pages = {1274--1281},
 title = {Novel siRNA Delivery System Using a Ternary Polymer Complex with Strong Silencing Effect and No Cytotoxicity},
 volume = {37},
 year = {2014}
}