Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697, USA.
Biomaterials. 2011 Jun;32(16):4009-20. doi: 10.1016/j.biomaterials.2011.02.010. Epub 2011 Mar 2.
Stimuli-responsive degradability is an indispensable design component for polymeric gene carriers. In order to obtain enhanced, non-cytotoxic, and molecularly tunable nonviral gene delivery, spermine, a bioavailable small cationic molecule, was polymerized with diacrylate cross-linkers with or without acid-degradable ketal linkages for controlled dual mode-degradability (i.e., differential degradations in the endosome and the cytosol). The effects of ketal to ester ratios in the polymeric backbone on degradation rate, condensation of both plasmid DNA and siRNA, cellular uptake, intracellular disassembly, and consequent DNA transfection and RNA interference efficiency in vitro and in vivo were investigated. Limited nucleic acid complexation and cellular uptake but efficient intracellular release of nucleic acids were obtained with poly(spermine ketal ester) (PSKE), the most acid-degradable polyspermine. In contrast, poly(spermine ester) (PSE), which is not acid-degradable, demonstrated efficient nucleic acid complexation and cellular uptake but inefficient intracellular release of nucleic acids. The highest in vitro DNA transfection was obtained by the random co-polymer of PSKE and PSE at an equal ratio (PSKE-PSE), attributed to its balanced DNA complexation and acid-responsive release efficiency, while efficient siRNA unpackaging by PSKE resulted in the highest gene silencing efficiency. Preliminary in vivo studies demonstrated that the highest DNA transfection was obtained by using PSE, while both PSKE and PSE silenced GFP expression at the similar level. In conclusion, dual mode-degradable polyspermine is a non-cytotoxic nonviral gene carrier, and its acid-degradability can be molecularly tuned for differentially controlled transfection and gene silencing in vitro and in vivo.
刺激响应降解性是聚合物基因载体不可或缺的设计组成部分。为了获得增强的、非细胞毒性的和分子可调的非病毒基因传递，可生物利用的小分子阳离子精胺与二丙烯酸酯交联剂聚合，带有或不带有酸降解缩酮键，以实现控制的双重模式降解性（即在内涵体和细胞质中的不同降解）。研究了聚合物主链中缩酮与酯的比例对降解速率、质粒 DNA 和 siRNA 的缩合、细胞摄取、细胞内解体以及随后的 DNA 转染和 RNA 干扰效率的影响。具有最酸降解性的聚（精胺缩酮酯）（PSKE）获得了有限的核酸复合物形成和细胞摄取，但有效地实现了核酸的细胞内释放。相比之下，不酸降解的聚（精胺酯）（PSE）表现出有效的核酸复合物形成和细胞摄取，但核酸的细胞内释放效率较低。PSKE 和 PSE 以相等比例的随机共聚物（PSKE-PSE）获得了最高的体外 DNA 转染效率，这归因于其平衡的 DNA 复合物形成和酸响应释放效率，而 PSKE 有效地解包装 siRNA 导致最高的基因沉默效率。初步的体内研究表明，使用 PSE 可获得最高的 DNA 转染效率，而 PSKE 和 PSE 均以相似的水平沉默 GFP 表达。总之，双重模式降解性聚精胺是一种非细胞毒性的非病毒基因载体，其酸降解性可以进行分子调节，以在体外和体内实现差异控制的转染和基因沉默。
