聚焦超声多次开放血脑屏障联合用药治疗脑胶质瘤的实验研究

Therapeutic opening of the blood brain barrier (BBB) and enhancing drug concentration in the target area are the keys determining the success or failure of chemotherapy treatment for glioma. Research up to the present demonstrates that the technique of using focused ultrasound conveying drug-loaded microbubbles can noninvasively open the BBB, and transfer the drug into the brain tissue target area. However, the results were revealed that the concentration in the region of interest was less than therapeutic dosage. We found that the size of tumor became small and the life span of rats with glioma was longer in the group of combination multiple BBB openings with drugs comparing with the group of single BBB opening or single drug after opening the BBB using focused ultrasound in our previous research. Based on the foundational experience, in order to further explore the main factors of impacting the stability of doxorubicin(DOX)-loaded liposomal microbubbles, and illuminate the mechanism of combination multiple BBB openings with drugs for treatment of glioma, now we will begin research: using MRI-guided focused ultrasound to blast DOX-loaded liposomal microbubbles to affect multiple openings in the BBB of rats with glioma. And the anti-angiogenesis drug, Avastin, will be utilized as the next step in the research is launched. This research is being done to evaluate the effectiveness and safety of treating glioma through a method that combines multiple BBB openings with drugs, and will be done by analyzing the physical characteristics of DOX-loaded liposomal microbubble, by comparing the life span of different groups of rats with glioma, by observing the changes in the morphous of tumor tissue and the ultrastructure of nerve cells, and by checking intracranial and extracranial DOX concentration. It will provide a theoretical basis for further clinical application of the method of using multiple BBB openings in combination with drugs to cure intracranial tumors effectively and noninvasively.

治疗性开放血脑屏障及提高局部药物浓度是决定脑胶质瘤化疗成败的关键。目前研究表明采用聚焦超声载药微泡技术可无创性地开放血脑屏障，靶向转运药物入脑组织，但结果显示局部组织药物浓度远达不到治疗剂量。针对这一问题，本项目前期研究显示聚焦超声开放脑胶质瘤大鼠血脑屏障后，联合用药及多次给药较单药单次给药，大鼠肿瘤体积缩小，生存期延长。在此基础上，为了进一步探讨影响载阿霉素脂质体微泡稳定性的主要因素，阐明多次开放血脑屏障和联合用药方案对脑胶质瘤的作用机制，拟应用MRI引导聚焦超声爆破载阿霉素脂质体微泡，联合抗新生血管药Avastin，多次开放脑胶质瘤大鼠血脑屏障。通过分析载阿霉素脂质体微泡的物理特性，比较各组荷瘤鼠生存期，观察瘤组织形态和神经细胞超微结构的变化，检测脑内外阿霉素浓度，以评估多次开放血脑屏障和联合用药方案对治疗脑胶质瘤的效果及安全性，为在临床上无创、靶向、高效治疗颅内肿瘤提供理论基础。

脑胶质瘤是最常见的中枢神经系统恶性肿瘤，具有高致残率、高复发率、高病死率和低治愈率的特点。由于神经胶质瘤特殊的浸润生长方式和独特的血脑屏障结构给治疗带来了极大的困难。研究一种新的开启血脑屏障并实现神经胶质瘤定点靶向输送药物的方法为提高肿瘤患者生存率和降低其死亡率均具有十分重要的意义。聚焦超声打开血脑屏障进行颅内给药为神经胶质瘤的无创治疗带来了新契机。基于以上事实，本研究提出一种聚焦超声开启血脑屏障递送特异性肿瘤药物治疗神经胶质瘤的方法，设计制备载阿霉素脂质体微泡，利用聚焦超声开启血脑屏障将靶向脂质体药物递送颅内肿瘤部位，释放阿霉素，从而特异性的杀伤肿瘤细胞。.本项目以在MRI引导下聚焦超声多次开放BBB、联合用药治疗脑胶质瘤的疗效和安全性为目标，分别按载阿霉素脂质体微泡的制备及特性评估，单次开放BBB、多次开放BBB、单次用药、联合用药后MRI测量肿瘤大小，HE染色观察瘤细胞凋亡情况，及药物含量测量等分别展开研究工作。结果显示阿霉素脂质体与Avastin联合、多次使用，大鼠肿瘤生长速度减慢，甚至缩小，生存期明显延长，说明聚焦超声联合微泡开放血脑屏障后，化疗药和抗新生血管药联合、多次应用对脑胶质瘤疗效确切显著。然而本实验周期较长；各组的样本量也远远不够；MRI图像质量、扫描时间等相关序列还需要在将来的实验中进一步优化。