Kichler A, Leborgne C, Coeytaux E, Danos O
Généthon III, CNRS URA 1923, Evry, France.
J Gene Med. 2001 Mar-Apr;3(2):135-44. doi: 10.1002/jgm.173.
Ethylenimine polymers (PEIs) belong to one of the most efficient family of cationic compounds for delivery of plasmid DNA into mammalian cells. The high transfection efficiencies are obtained even in the absence of endosomolytic agents such as fusogenic peptides or chloroquine, which is in contrast to most of the other cationic polymers. It has been hypothesized that the efficiency of PEI is due to its capacity to buffer the endosomes.
To investigate the importance of the acidification of endosomes during PEI-mediated DNA transfer we used proton pump inhibitors such as bafilomycin A1 and concanamycin A. Moreover, we tested whether PEI is able to destabilize natural membranes per se at neutral or acidic pH by performing erythrocyte lysis assays.
PEI-mediated transfection in the presence of bafilomycin A1 resulted in a 7-74-fold decrease in reporter gene expression depending on the cell line used. In contrast, the efficiency of the monocationic lipid, DOTAP, was not importantly altered in the presence of the drug. Furthermore, the present data show that PEI cannot destabilize erythrocyte membranes, even at acidic pH, and that PEI, complexed or not to DNA, can increase the transfection efficiency of the cationic polymer, polylysine, when added at the same time to the cells.
The transfection efficiency of PEIs partially relies on their ability to capture the protons which are transferred into the endosomes during their acidification. In addition, PEI is able to deliver significant amounts of DNA into cells and the DNA complexes involved in the expression of the transgene escape within 4 h from the endosomes.
乙撑亚胺聚合物（PEIs）属于将质粒DNA导入哺乳动物细胞的最有效的阳离子化合物家族之一。即使在没有诸如融合肽或氯喹等溶酶体溶解剂的情况下，也能获得高转染效率，这与大多数其他阳离子聚合物形成对比。据推测，PEI的效率归因于其缓冲溶酶体的能力。
为了研究在PEI介导的DNA转移过程中溶酶体酸化的重要性，我们使用了质子泵抑制剂，如巴弗洛霉素A1和 concanamycin A。此外，我们通过进行红细胞裂解试验，测试了PEI在中性或酸性pH下是否能够本身破坏天然膜的稳定性。
在巴弗洛霉素A1存在的情况下，PEI介导的转染导致报告基因表达根据所使用的细胞系下降7至74倍。相比之下，单阳离子脂质DOTAP的效率在药物存在的情况下没有明显改变。此外，目前的数据表明，即使在酸性pH下，PEI也不能破坏红细胞膜的稳定性，并且与DNA复合或未复合的PEI在与细胞同时添加时，可以提高阳离子聚合物聚赖氨酸的转染效率。
PEIs的转染效率部分依赖于它们捕获在溶酶体酸化过程中转移到溶酶体内的质子的能力。此外，PEI能够将大量DNA递送至细胞中，并且参与转基因表达的DNA复合物在4小时内从溶酶体中逃逸。
