不同相对分子质量聚乙烯亚胺体外介导基因传递的研究

Study on Different Molecular Weight of PEI as Carriers for Gene Delivery in Vitro

目的研究4种不同相对分子质量聚乙烯亚胺(PEI)作为非病毒基因载体体外介导基因传递的能力。方法采用四甲基噻唑蓝法(MTT法)测定了PEI对Hela细胞的毒性,利用琼脂糖凝胶电泳阻滞试验考察PEI与DNA的结合能力,测定PEI-DNA复合物的粒径和Zeta电位,以及考察转染率。结果PEI的细胞毒性与相对分子质量呈正相关,高相对分子质量PEI的细胞毒性远大于低相对分子质量PEI;高相对分子质量PEI在较低的N/P比时就能对DNA起到完全阻滞作用;低相对分子质量PEI与DNA形成的复合物粒径明显大于高相对分子质量的PEI;Zeta电位随着PEI相对分子质量的增大而增大,复合物的粒径和Zeta电位都与组成中的N/P比有关;相对分子质量为2000的PEI(PEI2K)在Hela细胞中的转染率最低,而相对分子质量为25000的PEI(PEI25K)的转染率最高。结论PEI的相对分子质量对其各项性能指标以及介导基因传递的能力都有较大影响。

Objective To study the property of different molecular weight of polyethylenimine（PEI） and its ability as nonviral carriers on gene delivery in vitro. Methods Cytotoxicity for Hela was evaluated by MTT assay; the capability of forming complexes between the posi- tively charged PEI and the negatively charged plasmid DNA was investigated by gel electrophoresis retardation assays; the complex size and zeta potential of PEI/DNA complexes were measured. And the transfection efficiency was investigated among different PEI/DNA. Results A positive correlation was showed between cytotoxicity and molecular weight. High molecular weight PEI was significantly more toxic than low molecular weight PEI. High molecular weight PEI had strong ability to condense DNA and could be retarded completely at a very low N/P. Low molecular weight PEI formed complexes with plasmid DNA which had significantly larger diameters than those of high molecular weight PEI. Zeta potential increased with increasing molecular weight of PEI. Particle sizes and zeta potentials were all influenced by N/P ratio. The transfection efficiency study showed PEI 2K yielded the lowest transfection and PEI 25K was found to be the most efficient gene carrier. Conclusion Different molecular weight of PEI has great influence on both the property and the ability for gene delivery. This research can provide experiment foundation for gene therapy and nonviral gene delivery system.