超声破坏LHRH-纳米微泡靶向递送、定位释放紫杉醇治疗卵巢癌的实验研究

Ovarian cancer is the leading cause of mortality compared with all other gynecological malignancies, which makes it become a hot issue but also a very difficult area to seek for targeted and efficient treatment. A new tactic is used at the present to treat the tumor effectively with the help of tumor specific ultrasound contrast agent which can send drugs to the target area. Then the ultrasound will monitor the appearance of microbubbles in target organs. Meanwhile, the ultrasound could cause microbubbles to rupture so that the drugs of high concentrations could be released locally in target tissues and kill tumor cells. In our previous research, we have successfully prepared LHRH-NM and verified its strong vascular penetration and tumor targeting. Based on the result of previous research, our project is aimed at conducting the following studies, hoping to provide a new idea and approach for target, efficient ovarian cancer chemotherapy : 1. to encapsule paclitaxel in LHRH-NM to produce paclitaxel-carrying LHRH-NM; 2. to detect physicochemical properties, drug entrapment efficiency and drug-loading amount; 3. to screen the experiment parameters recorded in ultrasound intensity and microbubbles concentration which have little effect on cell activity; 4. to investigate in vitro the special lethal effects of ultrasound on ovarian cells by LHRH-nano microbubbles loaded with paclitaxel; 5. to study ultrasonographic features, fluorescence distribution and tumor inhibition rate in tumor-bearing nude mice；6. to analyze in vivo paclitaxel tissue distribution and pharmacokinetic parameters after ultrasound destruction at different time points.

卵巢癌死亡率居妇科恶性肿瘤之首，寻求靶向、高效治疗方法是其研究的热点和难点。利用肿瘤特异性靶向微泡造影剂携载药物递送至治疗靶区，声像图监控下超声定时、定位击破载药微泡，于靶区内释放高浓度药物从而实现高效抗癌效应是肿瘤治疗的一种新策略。我们前期成功制备并验证了具有强血管穿透力和靶向结合卵巢癌的LHRH（促黄体生成素释放激素）-纳米微泡。基于该研究基础，本课题拟将高效化疗药物紫杉醇包封于LHRH-纳米微泡中构建载紫杉醇 LHRH-纳米微泡；检测载药微泡理化性质、药物包封率及释放率；筛选对卵巢癌细胞活性无明显影响的超声强度和载药微泡浓度实验参数；体外实验研究超声破坏载药微泡对卵巢癌细胞靶向杀伤效应；裸鼠肿瘤模型上研究载药微泡体内声像图特点、荧光分布及在超声可控击破释放药物后的靶向抗癌效应；分析载药微泡破坏后体内紫杉醇组织分布特点、药代动力学参数，为卵巢癌靶向、高效化疗提供新的思路和手段。

载药相变脂质纳米粒搭配超声兼具诊断性与治疗性功能，是相当有潜力的药物载体，同时提供物理性以及化学性的治疗效果。本实验制备的靶向卵巢癌的载紫杉醇相变脂质纳米粒（PTX-anti-LHRHR-PCNPs）联合低强度聚焦超声（LIFU）：一方面表现出比血细胞的更小的尺寸和更大的稳定性，使其在体内的半衰期显著延长，并且能够主动靶向卵巢癌OVCAR-3细胞，顺利透过内皮间隙到达肿瘤部位，对卵巢癌细胞予以特异性杀伤，从而提高治疗效果并降低毒副作用，最大限度地保护正常组织，将不良反应最小化；另一方面PTX-anti-LHRHR-PCNPs经静脉注入后能靶向因能聚集并较长时间滞留于肿瘤靶组织，同时在LIFU触发下能够发生液-气相变，产生较理想且持续的超声显影效果，再通过超声造影剂对超声的散射产生分子水平显影，从而实现从分子水平评价病变组织的应用。