正电荷载基因纳米微泡的超声成像及靶向杀伤肝癌细胞的研究

Study of cationic gene-loaded nanoscale microbubbles guided US imaging and targeted killing of hepatocellular carcinoma cells

目的:制备载基因纳米微泡并探讨其体内外超声成像和靶向杀伤肝癌细胞的效果。方法:采用薄膜水化-机械震荡法制备磷脂为壳膜、六氟化硫(suphurhexafluoride,SF6)气体为核心的正电荷纳米微泡,再偶联甲胎蛋白(alpha fetoprotein,AFP)启动子的单纯疱疹病毒胸苷激酶(simplex herpes virus thymidine kinase,HSV-TK)质粒DNA制备载基因纳泡。对其形态、平均粒径、zeta电位、DNA结合力、基因转染进行检测;然后对其体内外超声成像特性进行考察;最后采用CCK-8和流式细胞(FCM)分析检测载基因纳泡联合超声靶向微泡击破(ultrasound-targeted microbubble destruction,UTMD)技术对BEL-7402和SMCC-7721细胞的杀伤作用。结果:电镜显示纳泡呈圆球形壳核结构;平均水合粒径约为667 nm,带正电;琼脂糖凝胶电泳显示质量比≥5时,纳泡可有效结合质粒DNA;体内外超声显示载基因纳泡具有良好的超声对比增强特性;RT-PCR检测显示纳泡联合UTMD能使HSV-TK在AFP阳性肝癌细胞内表达。CCK-8和FCM分析显示载基因纳泡+UTMD组能显著抑制BEL-7402细胞的增殖和诱导其凋亡,与其他组相比差异具有显著性(P <0.05)。结论:具有良好超声成像功能的载基因纳泡能够高效靶向杀伤AFP阳性的肝癌细胞。

Objective:To prepare gene loaded nanaobubbles and explore their effects of ultrasonography and targeted killing of hepatocellular carcinoma cells in vivo and in vitro. Methods:Positively charged nanobubbles with the peripheml phospholipid shells filled by suphurhexafluoride(SF6)gas were fabricated through the method of lipid thin-film,hydration and mechanical agitations. Then simplex herpes virus thymidine kinase(HSV-TK)plasmid DNA coupled with alpha fetoprotein(AFP)promoter was conjugated to create gene loaded nanobubbles. The characteristics such as morphology,average particle size,zeta potential,capacity of DNA binding and gene transfection were detected. Then the effect of ultrasound contrast enhancement imaging was investigated in vivo and in vitro.Finally,the killing efficiency of gene-loaded nanobubbles on BEL-7402 and SMCC-7721 cells when combined with ultrasound-targeted microbubble destruction(UTMD)was detected using CCK-8 and flow cytometry(FCM)assay. Results:The nanobubbles appeared as a spherical morphology with a core-shell structure under TEM,and they were about 667 nm in mean hydrodynamic diameter with positive charge. Nanobubbles can effectively bind with plasmid DNA when particle/DNA weight ratio was set at 5∶1. The gene-loaded nanobubbles had good ultrasonic contrast enhancement characteristics in vitro and in vivo ultrasonography. RT-PCR assays indicated that nanobubbles combined with UTMD enabled HSV-TK to be expressed in AFP positive hepatocellular carcinoma cells rather than AFP negative ones. The analysis of CCK-8 and FCM showed that gene-loaded nanobubbles combined with UTMD could significantly inhibit the proliferation of BEL-7402 cells and induce apoptosis,which was significantly different from other groups(P < 0.05).Conclusion:Gene-loaded nanobubbles with good ultrasonic imaging function can effectively induce targeted killing of AFP positive hepatocellular carcinoma cells.