Li Yang, Li Junjie, Chen Biao, Chen Qixian, Zhang Guoying, Liu Shiyong, Ge Zhishen
CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China , Hefei, Anhui 230026, China.
Biomacromolecules. 2014 Aug 11;15(8):2914-23. doi: 10.1021/bm500532x. Epub 2014 Jul 11.
Adequate retention in blood circulation is a prerequisite for construction of gene delivery carriers for systemic applications. The stability of gene carriers in the bloodstream requires them to effectively resist protein adsorption and maintain small size in the bloodstream avoiding dissociation, aggregation, and nuclease digestion under salty and proteinous medium. Herein, a mixture of two block catiomers consisting of the same cationic block, poly{N-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} (PAsp(DET)), but varying shell-forming blocks, poly[2-(2-methoxyethoxy) ethyl methacrylate] (PMEO2MA), and poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA), was used to complex with plasmid DNA (pDNA) to fabricate polyplex micelles with mixed shells (MPMs) at 20 °C. The thermoresponsive property of PMEO2MA allows distinct phase transition from hydrophilic to hydrophobic by increasing incubation temperature from 20 to 37 °C, which results in a distinct heterogeneous corona containing hydrophilic and hydrophobic regions at the surface of the MPMs. Subsequent study verified that this transition promoted further condensation of pDNA, thereby giving rise to improved complex and colloidal stability. The proposed system has shown remarkable stability in salty and proteinous solution and superior tolerance to nuclease degradation. As compared with polyplex micelles formed from single POEGMA-b-PAsp(DET) block copolymer, in vivo circulation experiments in the bloodstream further confirmed that the retention time of MPMs was prolonged significantly. Moreover, the proposed system exhibited remarkably high cell transfection activity especially at low N/P ratios and negligible cytotoxicity and thus portends promising utility for systemic gene therapy applications.
对于构建用于全身应用的基因递送载体而言，在血液循环中充分保留是一个先决条件。基因载体在血流中的稳定性要求它们能够有效抵抗蛋白质吸附，并在血流中保持较小尺寸，以避免在含盐和含蛋白质的介质中发生解离、聚集和核酸酶消化。在此，使用由相同阳离子嵌段聚{N-[N-(2-氨基乙基)-2-氨基乙基]天冬酰胺}(PAsp(DET))组成，但壳形成嵌段不同的两种嵌段阳离子聚合物的混合物，聚2-(2-甲氧基乙氧基)乙基甲基丙烯酸酯和聚聚(乙二醇)甲基醚甲基丙烯酸酯，在20℃下与质粒DNA(pDNA)复合以制备具有混合壳的聚集体胶束(MPM)。PMEO2MA的热响应特性允许通过将孵育温度从20℃提高到37℃而从亲水性到疏水性发生明显的相转变，这导致在MPM表面形成包含亲水性和疏水性区域的明显异质冠状物。随后的研究证实，这种转变促进了pDNA的进一步凝聚，从而提高了复合物和胶体稳定性。所提出的系统在含盐和含蛋白质的溶液中显示出显著的稳定性，并且对核酸酶降解具有优异的耐受性。与由单一POEGMA-b-PAsp(DET)嵌段共聚物形成的聚集体胶束相比，在血流中的体内循环实验进一步证实，MPM的保留时间显著延长。此外，所提出的系统表现出非常高的细胞转染活性，尤其是在低N/P比时，并且细胞毒性可忽略不计，因此预示着在全身基因治疗应用中有广阔的应用前景。
