Shim Min Suk, Kwon Young Jik
Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
J Control Release. 2009 Feb 10;133(3):206-13. doi: 10.1016/j.jconrel.2008.10.007. Epub 2008 Nov 1.
To maximize therapeutic effects, targeted delivery of nucleic acids (e.g., DNA and RNA) in their appropriate intracellular targets is highly desirable. In this study, primary amines of a model polymeric nonviral carrier, polyethylenimine (PEI), at two molecular weights (0.8 and 25 kDa) were differentially ketalized (i.e., 17-96%) in order to explore the possibility of precisely modulating intracellular localization of plasmid DNA- and siRNA-containing polyplexes. The size of the polyplexes revealed that the ketalization ratios of 35 to 70% were found to be the most efficient in condensing nucleic acids with the ketalized low molecular weight PEI (LMW PEI), while high molecular weight PEI (HMW PEI) ketalized at the ratio of 23% condensed nucleic acids most efficiently. Ketalization of LMW PEI (up to 70%) enhanced transfection; however, ketalization of HMW PEI reduced its transfection capability. On the contrary, HMW PEI ketalized at 23 and 37% ratios showed significant RNA interference, while LMW PEI could not successfully inhibit gene expression regardless of ketalization ratios. The results were explained by confocal microscopic studies demonstrating that ketalization ratios, molecular weights of ketalized PEI, and types of nucleic acids complexed in the polyplexes play crucial roles in intracellular localization of nucleic acids/ketalized PEI polyplexes and affect DNA transfection and RNA interference efficiencies. All ketalized PEI showed negligible cytotoxicity. This study implies a feasibility of selectively localizing nucleic acids in their intracellular targets by employing differentially tailored polymeric gene carriers.
为了使治疗效果最大化，非常需要将核酸（如DNA和RNA）靶向递送至其合适的细胞内靶点。在本研究中，对两种分子量（0.8和25 kDa）的模型聚合物非病毒载体聚乙烯亚胺（PEI）的伯胺进行了不同程度的缩酮化（即17 - 96%），以探索精确调节含质粒DNA和siRNA的多聚体细胞内定位的可能性。多聚体的大小表明，对于缩酮化的低分子量PEI（LMW PEI），35%至70%的缩酮化率在凝聚核酸方面最有效，而缩酮化率为23%的高分子量PEI（HMW PEI）凝聚核酸最有效。LMW PEI的缩酮化（高达70%）增强了转染；然而，HMW PEI的缩酮化降低了其转染能力。相反，缩酮化率为23%和37%的HMW PEI表现出显著的RNA干扰，而LMW PEI无论缩酮化率如何都不能成功抑制基因表达。共聚焦显微镜研究解释了这些结果，表明缩酮化率、缩酮化PEI的分子量以及多聚体中复合的核酸类型在核酸/缩酮化PEI多聚体的细胞内定位中起关键作用，并影响DNA转染和RNA干扰效率。所有缩酮化的PEI均表现出可忽略不计的细胞毒性。本研究表明通过使用差异定制的聚合物基因载体将核酸选择性定位到其细胞内靶点具有可行性。
