Effect of Polymer Structure on Micelles Formed between siRNA and Cationic Block Copolymer Comprising Thiols and Amidines
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- 作者：R. James Christie ; Kanjiro Miyata ; Yu Matsumoto ; Takahiro Nomoto ; Daniel Menasco ; Tzai Chung Lai ; Matthew Pennisi ; Kensuke Osada ; Shigeto Fukushima ; Nobuhiro Nishiyama ; Yuichi Yamasaki ; Kazunori Kataoka
- 刊名：Biomacromolecules
- 出版年：2011
- 出版时间：September 12, 2011
- 年：2011
- 卷：12
- 期：9
- 页码：3174-3185
- 全文大小：1067K
- 年卷期：v.12,no.9(September 12, 2011)
- ISSN：1526-4602
文摘
Small interfering RNA (siRNA) has great therapeutic potential for the suppression of proteins associated with disease, but delivery methods are needed for improved efficacy. Here, we investigated the properties of micellar siRNA delivery vehicles prepared with poly(ethylene glycol)-block-poly(l-lysine) (PEG-b-PLL) comprising lysine amines modified to contain amidine and thiol functionality. Lysine modification was achieved using 2-iminothiolane (2-IT) [yielding PEG-b-PLL(N2IM-IM)] or dimethyl 3,3鈥?dithiobispropionimidate (DTBP) [yielding PEG-b-PLL(MPA)], with modifications aimed to impart disulfide cross-linking ability without compromising cationic charge. These two lysine modification reagents resulted in vastly different chemistry contained in the reacted block copolymer, which affected micelle formation behavior and stability along with in vitro and in vivo performance. Amidines formed with 2-IT were unstable and rearranged into a noncharged ring structure lacking free thiol functionality, whereas amidines generated with DTBP were stable. Micelles formed with siRNA and PEG-b-PLL(N2IM-IM) at higher molar ratios of polymer/siRNA, while PEG-b-PLL(MPA) produced micelles only near stoichiometric molar ratios. In vitro gene silencing was highest for PEG-b-PLL(MPA)/siRNA micelles, which were also more sensitive to disruption under disulfide-reducing conditions. Blood circulation was most improved for PEG-b-PLL(N2IM-IM)/siRNA micelles, with a circulation half-life 3脳 longer than naked siRNA. Both micelle formulations are promising for siRNA delivery applications in vitro and in vivo.