Kodama Yukinobu
Department of Pharmacy Practice, Graduate School of Biomedical Sciences, Nagasaki University.
Yakugaku Zasshi. 2016;136(11):1533-1539. doi: 10.1248/yakushi.16-00198.
Nucleic acids are expected as novel effective medicines, although they require a drug delivery system (DDS). Complexes of nucleic acids with cationic liposomes and cationic polymers have been mainly used as DDS for clinical use. However, most cationic complexes have disadvantages such as strong cytotoxicity and low biocompatibility. We previously found that a plasmid DNA (pDNA) complex coated with biodegradable γ-polyglutamic acid (γ-PGA) provided adequate gene expression without cytotoxicity. Based on these results, we developed a new DDS (multi-functional Nano-device) of pDNA using biodegradable polyamino acids. A typical cationic polyamino acid, poly-L-lysine (PLL), was complexed with pDNA. The binary complexes, however, showed low gene expression and high cytotoxicity. Gene expression was enhanced by addition of poly-L-histidine (PLH) to the binary complexes. PLH can increase endosome escape of the complexes by inducing pH-buffering effects. The quaternary complexes (pDNA-PLL-PLH-γ-PGA complexes) exhibited high gene expression and low cytotoxicity. Furthermore, we used dendrigraft poly-L-lysine (DGL) instead of PLL and PLH to enhance gene expression. DGL had sterically congested cations and was biodegradable. The ternary complexes (pDNA-DGL-γ-PGA complexes) exhibited markedly high gene expression and low cytotoxicity. The pDNA-DGL-γ-PGA complexes also had high gene expression in the marginal zone (rich dendritic cells) of the spleen after intravenous injection into mice. These results indicate that pDNA-DGL-γ-PGA complexes may be useful as vaccine vectors. Therefore we prepared a novel malaria DNA vaccine using Plasmodium yoelii GPI8p-transamidase-related protein pDNA (PyTAM). The PyTAM-DGL-γ-PGA complexes markedly improved survival time of model mice infected with malaria.
核酸有望成为新型有效药物，尽管它们需要药物递送系统（DDS）。核酸与阳离子脂质体和阳离子聚合物的复合物主要用作临床应用的DDS。然而，大多数阳离子复合物存在诸如强细胞毒性和低生物相容性等缺点。我们之前发现，用可生物降解的γ-聚谷氨酸（γ-PGA）包被的质粒DNA（pDNA）复合物可提供足够的基因表达且无细胞毒性。基于这些结果，我们利用可生物降解的聚氨基酸开发了一种新的pDNA药物递送系统（多功能纳米装置）。一种典型的阳离子聚氨基酸聚-L-赖氨酸（PLL）与pDNA复合。然而，二元复合物显示出低基因表达和高细胞毒性。通过向二元复合物中添加聚-L-组氨酸（PLH）可增强基因表达。PLH可通过诱导pH缓冲效应增加复合物的内体逃逸。四元复合物（pDNA-PLL-PLH-γ-PGA复合物）表现出高基因表达和低细胞毒性。此外，我们使用树枝状接枝聚-L-赖氨酸（DGL）代替PLL和PLH来增强基因表达。DGL具有空间拥挤的阳离子且可生物降解。三元复合物（pDNA-DGL-γ-PGA复合物）表现出明显高的基因表达和低细胞毒性。将pDNA-DGL-γ-PGA复合物静脉注射到小鼠体内后，其在脾脏边缘区（富含树突状细胞）也具有高基因表达。这些结果表明，pDNA-DGL-γ-PGA复合物可能作为疫苗载体有用。因此，我们使用约氏疟原虫GPI8p-转酰胺酶相关蛋白pDNA（PyTAM）制备了一种新型疟疾DNA疫苗。PyTAM-DGL-γ-PGA复合物显著提高了感染疟疾的模型小鼠的存活时间。
