磁性高分子载体用于基因释放及MRI监测

Magnetic Polymer Gene Vector for Gene Delivery and MRI Monitoring

目的:研究阳离子高分子基因载体聚乙烯亚胺(PEI)修饰的氧化铁-质粒DNA磁性纳米颗粒用于磁性基因转染、基因释放及MRI监测的可行性与效果。方法:采用PEI修饰超顺磁性氧化铁纳米颗粒(PEI-MNPs)并结合增强型绿色荧光蛋白质粒(EGFP)DNA,构建氧化铁-质粒DNA磁性纳米颗粒(DNA-MNPs)。测量PEIM NPs及DNA-M NPs粒径及Zeta电位。采用磁性转染法,在外加磁场下,将DNA-M NPs与人肝癌Bel7402细胞共孵育,并与常规转染法对照,比较两种转染方法的绿色荧光蛋白表达的差异。采用MRI-T2WI成像测量两组转染细胞悬液不同时间点的T2弛豫率。结果:分散状态的PEI-MNPs与聚合状态的DNA-MNPs平均粒径分别约为15nm及850nm。DNA-MNPs的Zeta电位与Fe/DNA比值呈正比。磁性转染组在转染前、转染后1h及24h肝癌细胞悬液T2弛豫率分别为1.67、4.95、14.7,而常规转染组分别为1.61、2.23、3.226。磁性转染组绿色荧光蛋白表达强度显著高于常规转染组。结论:PEI-MNPs用于磁性转染能显著提高基因转染效率,MRI能监测DNA-MNPs在细胞内释放质粒DNA前后所引起的T2弛豫率变化。

Purpose： To study the feasibility and effect of using the DNA-MNPs polyplexes comprised of PEI coated magnetic iron oxide nanoparticles and the plasmid DNA for magnetic gene transfection, gene release and MRI monitoring. Methods： The DNA-MNPs polyplexes, which was comprised of PEI coated magnetic iron oxide nanoparticles and plasmid DNA of enhanced green fluorescent protein （EGFP）, was synthetized. The average diameter and the particle Zeta potential of the DNA-MNPs and PEI-MNPs was observed and measured. Ex vivo magneto-transfection experiment was done by which human hepatoearcinoma Be17402 cells were cultivated with DNA-MNPs under a magnetic field. The difference of GFP expressing between standard transfection group and the magneto-transfection group was compared. T2 relaxation time of cultivated cell suspension in two groups at the different time point was measured by MRI. Results： The mean size of the dispersed PEI-MNPs was 15 nm, while that of the DNA-MNPs polyplexes was 850nm. The Zeta potential of the DNA-MNPs complexes was closely related to the Fe/DNA ratios. The T2 relaxation time of the Be17402 cells prior of gene transfection, 1 and 24h after gene transfection was 1.67, 4.95, 14.7 in magneto-transfection group, and 1.61, 2.23, 3.226 in standard transfection group. GFP expressing in magneto-transfection group was much higher than that in standard transfection group. Conclusion： The gene transfection efficiency can be greatly improved by applying the PEI-MNPs polyplexes for magneto-transfection. The change of T2 relaxivity caused by DNA-MNPs polyplexes releasing plasmid DNA in the cell can be monitored by MRI.