Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA 52242, United States.
Int J Pharm. 2012 May 1;427(1):71-9. doi: 10.1016/j.ijpharm.2011.10.032. Epub 2011 Oct 21.
Polyethylenimine (PEI) is a cationic polymer that is an efficient transfection reagent marred by high toxicity and a susceptibility to aggregate in the presence of serum. Dextran is a biodegradable natural polysaccharide that can be used to reduce the toxicity of PEI and increase its stability in the presence of serum. In this study, small branched PEI units (800/2000 Da) were attached to dextran (Dex; 15/100-200 kDa) to form dextran-polyethylenimine (Dex-PEI) conjugates. The Dex-PEI conjugates were then tested as a gene carrier in the model HEK293 cell line. Dex-PEI conjugates displayed significantly lower cytotoxicity than PEI (25k). Both Dex-PEI and PEI efficiently delivered firefly luciferase encoded plasmid DNA (pDNA) to the HEK293 cells. Dex-PEI resulted in moderately lower transfection efficiencies than PEI 25k when the transfection was carried out in media without serum for 4h. However, in the presence of serum, which more accurately predicts the anticipated environment of non-viral vectors in vivo, Dex-PEI and unmodified PEI generated similar transfection efficiencies when incubated with the cells for 4h. When the incubation time of the vectors was increased to 48h, significantly higher transfection efficiencies were generated by Dex-PEI in comparison to PEI. Turbidity measurements showed that complexes formed between plasmid DNA and unmodified PEI were more susceptible to aggregation in serum-containing media than complexes formed from pDNA and Dex-PEI. Dex-PEI conjugates are therefore believed to have greater potential for translational applications because of lower cytotoxicity characteristics and improved stability in serum containing environments.
聚乙烯亚胺（PEI）是一种阳离子聚合物，作为高效转染试剂，其毒性高，且在有血清存在的情况下容易聚集。葡聚糖是一种可生物降解的天然多糖，可用于降低 PEI 的毒性并提高其在血清存在下的稳定性。在本研究中，将小支化的 PEI 单元（800/2000Da）连接到葡聚糖（Dex；15/100-200kDa）上，形成葡聚糖-聚乙烯亚胺（Dex-PEI）缀合物。然后将 Dex-PEI 缀合物作为基因载体在模型 HEK293 细胞系中进行测试。与 PEI（25k）相比，Dex-PEI 缀合物显示出明显更低的细胞毒性。Dex-PEI 和 PEI 都能有效地将萤火虫荧光素酶编码质粒 DNA（pDNA）递送到 HEK293 细胞中。在无血清的培养基中进行转染 4 小时时，Dex-PEI 的转染效率略低于 PEI 25k，但在含有血清的情况下，更准确地预测了非病毒载体在体内的预期环境，Dex-PEI 和未修饰的 PEI 在与细胞孵育 4 小时时产生相似的转染效率。当载体孵育时间延长至 48 小时时，与 PEI 相比，Dex-PEI 产生的转染效率显著更高。浊度测量表明，在含有血清的培养基中，与 pDNA 和 Dex-PEI 形成的复合物相比，与未修饰的 PEI 形成的复合物更容易聚集。因此，由于具有更低的细胞毒性特征和在含有血清的环境中的稳定性提高，Dex-PEI 缀合物具有更大的转化应用潜力。
