One of the most popular nonviral delivery systems for gene therapy constructs are carriers based on polyethylenimine (PEI) DNA complexes. A number of disadvantages associated with the lack of targeted delivery and increased cytotoxicity are overcome by adding auxiliary molecules to the complexes. An example of this is chondroitin sulfate (CS). The purpose of this work was to assess the effect of CS on the transfection properties of DNA–PEI complexes under different conditions of their preparation and transfection protocols. All complexes were prepared in solutions with high and low ionic strength. Transfection of C26 cells was performed according to two protocols differing in the presence of serum in the medium. The portion of transfected cells, transgene expression level, and cell viability were the main parameters of assessing the transfection efficiency. In binary DNA–PEI complexes prepared in different salt conditions, using different transfection protocols, the difference in the portion of transfected cells reached ten times. Addition of CS improved this transfection efficiency indicator up to 6.5 times, while the maximum difference in this indicator for the corresponding ternary complexes was reduced to 2.5 times. Changes in the proportion of CS in the composition of the complexes had an insignificant effect on their transfection properties. In the case of complexes prepared in high ionic strength solutions, the order of CS addition was also important. The best results of transfection efficiency were achieved with ternary complexes prepared in low ionic strength solutions, using a serum-free protocol, while these indicators were comparable with the data for Lipofectamine 2000. The addition of chondroitin sulfate improves the transfection properties of DNA–PEI complexes and makes them less dependent on the methods of preparation and transfection.

中文翻译：

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硫酸软骨素通过 DNA-PEI 复合物提高转染效率

用于基因治疗构建体的最流行的非病毒递送系统之一是基于聚乙烯亚胺 (PEI) DNA 复合物的载体。通过向复合物中添加辅助分子，克服了与缺乏靶向递送和增加的细胞毒性相关的许多缺点。这方面的一个例子是硫酸软骨素 (CS)。这项工作的目的是评估 CS 对 DNA-PEI 复合物在其制备和转染方案的不同条件下转染特性的影响。所有配合物均在具有高离子强度和低离子强度的溶液中制备。C26 细胞的转染根据两种不同的方案在培养基中存在血清的情况下进行。转染细胞的部分，转基因表达水平，和细胞活力是评估转染效率的主要参数。在不同盐条件下制备的二元 DNA-PEI 复合物中，使用不同的转染方案，转染细胞的部分差异达到了 10 倍。CS 的加入将该转染效率指标提高了 6.5 倍，而相应三元复合物的该指标的最大差异减少到 2.5 倍。复合物组成中 CS 比例的变化对其转染特性的影响不显着。在高离子强度溶液中制备复合物的情况下，CS 添加的顺序也很重要。使用无血清方案，在低离子强度溶液中制备的三元复合物获得了最佳的转染效率结果，