Intramuscular expression of functional proteins is a promising strategy for therapeutic purposes. Previously, we developed an intramuscular gene delivery method by combining Pluronic L64 and optimized electropulse, which is among the most efficient methods to date. However, plasmid DNAs (pDNAs) in this method were not compressed, making them unstable and inefficient in vivo. We considered that a proper compression of pDNAs by an appropriate material should facilitate gene expression in this L64-electropulse system. Here, we reported our finding of such a material, Epigallocatechin gallate (EGCG), a natural compound in green teas, which could compress and protect pDNAs and significantly increase intramuscular gene expression in the L64-electropulse system. Meanwhile, we found that polyethylenimine (PEI) could also slightly improve exogenous gene expression in the optimal procedure. By analysing the characteristic differences between EGCG and PEI, we concluded that negatively charged materials with strong affinity to nucleic acids and/or other properties suitable for gene delivery, such as EGCG, are better alternatives than cationic materials (like PEI) for muscle-based gene delivery. The results revealed that a critical principle for material/pDNA complex benefitting intramuscular gene delivery/expression is to keep the complex negatively charged. This proof-of-concept study displays the breakthrough in compressing pDNAs and provides a principle and strategy to develop more efficient intramuscular gene delivery systems for therapeutic applications.

中文翻译：

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在 Pluronic L64 电脉冲系统中压缩和保护质粒 DNA 的正确策略，以增强肌内基因递送。

功能蛋白的肌内表达是一种有前途的治疗策略。此前，我们通过结合 Pluronic L64 和优化的电脉冲开发了一种肌内基因递送方法，这是迄今为止最有效的方法之一。然而，该方法中的质粒 DNA (pDNA) 并未被压缩，导致其在体内不稳定且效率低下。我们认为，用适当的材料对 pDNA 进行适当的压缩应该有助于 L64 电脉冲系统中的基因表达。在这里，我们报告了我们发现的一种材料，即表没食子儿茶素没食子酸酯（EGCG），它是绿茶中的一种天然化合物，它可以压缩和保护 pDNA，并显着增加 L64 电脉冲系统中的肌内基因表达。同时，我们发现聚乙烯亚胺（PEI）在最佳程序下也可以略微提高外源基因的表达。通过分析 EGCG 和 PEI 之间的特征差异，我们得出结论，对于核酸和/或其他适合基因传递的特性具有强亲和力的负电荷材料（例如 EGCG）是比阳离子材料（例如 PEI）更好的替代品，用于基于肌肉的基因传递。结果表明，有利于肌内基因递送/表达的材料/pDNA复合物的一个关键原则是保持复合物带负电荷。这项概念验证研究展示了压缩 pDNA 方面的突破，并提供了开发更有效的肌肉内基因递送系统用于治疗应用的原理和策略。