新型靶向纳米材料介导基因治疗胶质瘤的体外研究

Synthesis and characterization of novel nonviral vectors for tumor-targeted gene delivery to C6 glioma cells in vitro

目的:合成可降解性叶酸(FA)-PEG-PEI和PEG-PEI并研究其负载质粒DNA的能力,比较所形成纳米材料/DNA复合物在体外对细胞的毒性大小及其转染效率,为进一步体内基因治疗做好准备。方法:化学方法合成可降解性FA-PEG-PEI和PEG-PEI,检测所形成纳米材料/DNA复合物的粒径、zeta-电位和凝胶阻滞能力,以及对C6(叶酸受体中度表达)、293T(叶酸高度表达)和HepG2(叶酸不表达)3种细胞的细胞毒性,并对3种细胞进行转染,分别用流式细胞仪、荧光素酶基因表达水平和倒置荧光显微镜检测转染效果。结果:FA-PEG-PEI与PEG-PEI复合pDNA后进行电位、粒度分析表明其带正电,粒径在200～300nm,FA-PEG-PEI和DNA的完全结合在N/P比为5,PEI和PEG-PEI与DNA的完全结合则出现在N/P比为10。MTT法证实了复合物在C6、293T、HepG23种细胞中的细胞毒性表明其细胞毒性比常用的PEI25ku低;在3种细胞中,转染效率从整体来看,N/P比=15时,FA-PEG-PEI萤光素酶基因表达水平最高;类似的,通过流式细胞仪和倒置荧光显微镜更直观的检测了转染效果,表明FA-PEG-PEI对C6、293T细胞都有靶向效果且在N/P比为15时靶向效果最好,而在HepG2细胞中没有靶向效果。结论:此研究结果为叶酸靶向基因治疗神经胶质瘤寻找行之有效的基因载体提供了理论和实践基础,可进一步于动物体内进行联合基因治疗神经胶质瘤。

Objective:To enhance the transfection efficiency and to reduce the toxicity of the polyethyleneimine(PEI),we synthesized PEI derivatives and tested their toxicity and transfection efficiency in different cell lines. Methods:We first developed PEGylated PEI to decrease the toxicity of PEI,and then we conjugated folate on the distal end of the novel PEG-PEI to introduce specificity for special tumor cells.Following we checked the characterization of polymers and tested their toxicity and transfection efficiency in three cell lines with MTT assay,EGFP/fluorescent image,reporter assay and flow cytometry. Results:These copolymers effectively condensed plasmid DNA(pDNA) into nanoparticles with positive surface charge under a sui table N/P ratio.These derivatives reduced the cytotoxicity of PEI 25ku in different cell lines(i.e.,HEK 293T,glioma C6 and hepatoma HepG2 cells).More importantly,compared with PEI 25ku,the transfection efficiency was increased. Reporter assay and flow cytometry showed that FA-PEG-PEI/pDNA complexes exhibited higher transgene activity than that of PEG-PEI/pDNA or PEI/pDNA in folate-receptor(FR) positive(HEK 293T and C6) cells but not FR-negative(HepG2) cells. Conclusion:These results indicated that FA-PEG-PEI might be a promising candidate for gene delivery with the characteristic of good biocompatibility and relatively high gene transfection efficiency.