Effect of Polymer Structure on Micelles Formed between siRNA and Cationic Block Copolymer Comprising Thiols and Amidines
Effect of Polymer Structure on Micelles Formed between siRNA and Cationic Block Copolymer Comprising Thiols and Amidines
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DOI：
10.1021/bm2006714
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发表时间：
2011-09-01
影响因子：
6.2
通讯作者：
Kataoka, Kazunori
中科院分区：
文献类型：
--
作者：
Christie, R. James;Miyata, Kanjiro;Kataoka, Kazunori
小干扰 RNA (siRNA) 在抑制与疾病相关的蛋白质方面具有巨大的治疗潜力，但需要采用递送方法来提高疗效。在这里，我们研究了用聚（乙二醇）-嵌段-聚（L-赖氨酸）（PEG-b-PLL）制备的胶束 siRNA 递送载体的特性，该载体包含经过修饰以含有脒和硫醇官能团的赖氨酸胺。使用 2-亚氨基四氢噻吩 (2-IT) [产生 PEG-b-PLL(N2IM-IM)] 或 3,3'-硫代双丙亚胺酸二甲酯 (DTBP) [产生 PEG-b-PLL(MPA)] 实现赖氨酸修饰，修饰旨在赋予二硫键交联能力而不损害阳离子电荷。这两种赖氨酸修饰试剂导致反应后的嵌段共聚物中含有截然不同的化学成分，从而影响胶束形成行为和稳定性以及体外和体内性能。用 2-IT 形成的脒不稳定，会重排成缺乏游离硫醇官能团的不带电荷的环结构，而用 DTBP 生成的脒是稳定的。 siRNA和PEG-b-PLL(N2IM-IM)以较高的聚合物/siRNA摩尔比形成胶束，而PEG-b-PLL(MPA)仅产生接近化学计量摩尔比的胶束。 PEG-b-PLL(MPA)/siRNA 胶束的体外基因沉默最高，其在二硫键还原条件下对破坏也更敏感。 PEG-b-PLL(N2IM-IM)/ siRNA 胶束的血液循环得到最大改善，循环半衰期比裸 siRNA 长 3 倍。两种胶束制剂都有望用于体外和体内 siRNA 递送应用。
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'-clithiobispropionimidate (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 x longer than naked siRNA. Both micelle formulations are promising for siRNA delivery applications in vitro and in vivo.