利用经颅磁刺激仪构建灯盏乙素磁性纳米递药系统的研究

Ischemic stroke has the characteristics of high morbidity, high fatality rate and high disability rate. The application of its only special treatment—thrombolysis and thrombectomy, is restricted due to the narrow treatment window. Thus, it is urgent to study a new treatment method for the ischemic stroke. Scutellarin is the main and effective component of traditional Chinese medicine Erigeron breviscapus (Vant.) Hand.-Mazz., which is the effective drug for the treatment of ischemic cardio-cerebrovascular diseases clinically. However, the water solubility of scutellarin is poor, which limits its clinical application. We aim to improve the water solubility and targeting ability of scutellarin using ferromagnetic nanoparticles. But at present, the researches about magnetic targeted drug delivery mainly concentrate on the tumors near the surface of the body. The reason is that the magnetic field produced by the permanent magnet or electromagnet is difficult to reach the deep tissue, but the alternating magnetic field has stronger penetrating force. Therefore, we plan to use the alternating magnetic field generated by transcranial magnetic stimulator to direct the magnetic nanoparticles loaded with scutellarin to the brain and release the scutellarin for the treatment of ischemic stroke. Box-behnken response surface experimental design method is used to optimize the properties of magnetic nanoparticles, and to explore the requirements of dose and magnetic field. As a result, a magnetic-driven targeted delivery system for scutellarin is established. Its targeted therapeutic effect will be evaluated. It is hoped that the targeted drug delivery system can provide a new therapeutic method for ischemic cerebrovascular diseases.

缺血性脑卒中具有发病率高、病死率高、致残率高的特点，其仅有的特效治疗—溶栓和取栓，由于其狭窄的治疗窗限制了其应用，在临床治疗中迫切需要研究新的治疗方法。灯盏乙素为民族药灯盏花的主要药效成分，是治疗缺血性心脑血管疾病的有效药物，在临床上广泛应用。但是灯盏乙素的水溶性差，限制其临床应用效果。本项目拟利用四氧化三铁磁性纳米颗粒改善其水溶性，提高其靶向性。但是基于永磁铁或电磁铁产生磁场的磁性靶向药物研究主要集中在距离体表较近的肿瘤，很难达到较深部的组织，而交变磁场的穿透力较强。因此本项目拟利用经颅磁刺激仪产生的交变磁场引导灯盏乙素磁性纳米颗粒到达脑部，释放药物治疗缺血性脑卒中，并通过Box-Behnken效应面实验设计方法优化载药磁性纳米颗粒，探求所需的剂量和磁场条件，最终建立一种基于磁驱动的灯盏乙素靶向递药系统，并对其靶向治疗效果进行研究，以期为缺血性脑血管疾病提供一种新的治疗方法。

中药治疗中风病历史久远。其中灯盏乙素是从天然植物灯盏花中提取的黄酮类活性成分，主要用于治疗缺血性心脑血管疾病，在临床上广泛应用。但灯盏乙素的水溶性差，限制其临床应用效果。本项目利用生物可降解载体材料聚乳酸-羟基乙酸共聚物（PLGA）负载灯盏乙素（SCU），并在其中加入磁性四氧化三铁（Fe3O4）纳米颗粒制备得到灯盏乙素磁性纳米粒（SCU MNPs）。通过Box-Behnken效应面法优化处方，得到性能优良的SCU MNPs，并通过透射电镜、激光粒度分析仪等对其形貌、粒径大小进行表征，通过紫外可见光谱和红外光谱对其组成进行确认。体外药物释放实验证实PLGA的包裹的确可以提高SCU的水溶性和稳定性，并对其释放有一定缓释作用，其释药曲线符合Hixson-Crowell方程，为聚合物溶胀和聚合物链松弛控制的药物释放。以吲哚菁绿（ICG）替代SCU制备ICG磁性纳米粒，通过小动物活体成像仪观察到ICG磁性纳米粒在磁铁引导下的脑靶向作用。采用高效液相色谱和高效液相色谱质谱联用仪建立灯盏乙素体内外含量测定方法，通过测定模型大鼠脑内灯盏乙素的含量，确定经颅磁刺激仪的最佳磁场条件为磁感应强度II档（6mT～9mT）作用30min，SCU MNPs的含铁量要高于8.6μg/mL方能被引导入脑。经神经功能缺损评分、TTC染色测定脑梗死面积、HE染色观察病变组织变化、TUNEL测定细胞凋亡率综合评价SCU MNPs的治疗效果，通过SOD、MDA、NO、TNF-α、IL-6试剂盒阐释SCU、SCU MNPs及便携式经颅磁刺激仪的抗氧化抗炎效果。实验结果显示游离的SCU和SCU MNPs具有相似的脑缺血再灌注损伤治疗效果；磁铁（静磁场）引导SCU MNPs到达脑部治疗脑缺血再灌注损伤的效果与无磁场作用的SCU MNPs的治疗效果相当；便携式经颅磁刺激仪对脑缺血再灌注损伤没有明显的治疗效果，但具有一定的抗氧化作用；在便携式经颅磁刺激仪（交变磁场）引导下的SCU MNPs治疗效果明显优于游离的SCU和SCU MNPs，这可能与便携式经颅磁刺激仪和灯盏乙素发挥协同作用有关。最终利用便携式经颅磁刺激仪构建得到灯盏乙素磁性靶向递药系统，是治疗缺血性脑血管疾病的有效方法。