siRNA-loaded nanoparticles (NPs) administered systemically can overcome the poor stability and rapid elimination of free double-stranded RNA in circulation, resulting in increased tumor accumulation and efficacy. siRNA against osteopontin (siOPN), a protein involved in breast cancer development, was encapsulated in poly(D,L-lactic-co-glycolic acid) NPs by a double emulsion solvent diffusion (DESD) technique. We also compared the effect of polyethylenimine (PEI) molecular weight (800 Da and 25 kDa), used as the counter-ion for siRNA complexation, on the physicochemical properties of the NPs, cytotoxicity, and cellular uptake.NPs prepared by the DESD technique were obtained at the desired size (∼170 nm) using both types of PEIs, and were characterized with a neutral surface charge, high encapsulation yield (up to ∼60%), siOPN concentration of 5.6–8.4 μg/mg, stability in physiologic conditions in vitro and in vivo, and long-term self-life stability (> 3 years). The NPs prepared using both PEIs exhibited no cytotoxicity in primary smooth muscle culture, and no detrimental effect on mice liver enzymes following their IV administration. Following cellular uptake and biodistribution studies, the therapeutic potential of the NPs was demonstrated by a significant decrease of tumor progression and size in an ectopic xenograft model of mammary carcinoma in mice.

中文翻译：

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通过双乳液溶剂扩散技术制备的siRNA聚合纳米颗粒：在乳腺癌小鼠模型中的理化特性，毒性，生物分布和功效

全身施用载有siRNA的纳米颗粒（NPs）可以克服稳定性差和循环中游离双链RNA的快速消除，从而增加肿瘤的积累和疗效。针对骨桥蛋白（siOPN）的siRNA（一种参与乳腺癌发展的蛋白）被包裹在poly（D，L-lactic- co-乙醇酸NPs通过双乳液溶剂扩散（DESD）技术。我们还比较了用作siRNA络合抗衡离子的聚乙烯亚胺（PEI）分子量（800 Da和25 kDa）对NP的理化性质，细胞毒性和细胞摄取的影响。通过DESD技术制备的NP两种类型的PEI均以所需的大小（〜170 nm）获得，并具有中性表面电荷，高包封率（高达〜60％），siOPN浓度为5.6–8.4μg/ mg，生理稳定性的特征条件在体外和体内，以及长期的自我生命稳定性（> 3年）。使用两种PEI制备的NP在初次平滑肌培养中均未显示出细胞毒性，并且在静脉注射后对小鼠肝酶没有有害影响。在细胞摄取和生物分布研究之后，NPs的治疗潜力在小鼠乳腺异位异种移植模型中的肿瘤进展和大小显着减少中得到证实。