联合光动力和化学治疗的靶向混合胶束用于抗脑胶质瘤的研究

Glioma is the most common form of malignant tumor in the central nervous system in humans. Traditional therapeutic treatments are often compromised due to the difficulty of anti-tumor agents across several physiologic barriers to glioma sites. For this reason, there is great need to explore novel therapeutic regimens, especially highly effective targeted drug delivery systems to improve the curative outcome of gliomas. In our previous studies, we found that the combined photodynamic and chemo-therapy affected multiple pathways in glioma growth and development. We also found drug delivery system composed of functional materials could facilitate drugs crossing the blood brain barrier (BBB). Moreover, the drug delivery system, when modified with targeting group, could effectively deliver drugs to gliomas while reduce the toxicity to healthy tissues. Based on our previous findings, a novel Pluronic-based mixed micellar drug-delivery system loaded with both photosensitizer and chemotherapy agents for glioma treatment is proposed, which adopts Pluronic for inhibiting the drug efflux on the BBB. Further modification with tissue factor will endow the micellar system with glioma- and neovascular-homing abilities, thus forming a powerful mixed micelle targeted drug delivery system for combined photodynamic and chemo- therapy. In this program, the drug efflux inhibition, glioma targeting, anti-glioma efficacy and detailed mechanism behind this novel drug delivery system will be thoroughly evaluated and investigated both in vitro and in vivo.

脑胶质瘤是中枢神经系统最常见的恶性肿瘤，但由于其部位的特殊性，诸多生理屏障阻碍了药物到达胶质瘤部位，使治疗效果大大降低。因此，亟待寻找新的治疗方案和高效的递药系统解决脑胶质瘤的治疗难和疗效差的问题。我们在前期工作中发现，通过将光动力疗法与化学疗法相结合，可以作用于脑胶质瘤生长与发展过程中的多个环节；通过具有功能性的载体构建递药系统，可以增加药物入脑量；通过高效的靶向基团修饰可以提高对脑胶质瘤的靶向性，降低对正常组织的毒性。本项目拟在前期工作的基础上，同时以光敏剂和化学药物作为模型药物，采用具有抑制血脑屏障上蛋白外排功能的普朗尼克作为载体材料构建混合胶束系统，并通过修饰组织因子配体的策略，靶向组织因子高表达的脑胶质瘤细胞和脑胶质瘤新生血管细胞，构建联合光动力和化学治疗的靶向混合胶束系统，并进行体内外抗脑胶质瘤的研究。

光动力疗法（PDT）作为目前较为新颖的抗肿瘤手段，具有无耐药性，可局部杀伤，广谱性好等优势，已受到人们广泛关注。抗肿瘤光动力治疗的主要局限之处在于多数光敏剂溶解度低，易聚集且难以定向蓄积于肿瘤部位。因此，本课题基于合成得到的TPGS-RGD和VES-g-CSO这两种载体材料，采用有机溶剂挥发法制备了包载疏水性光敏剂替莫泊芬（mTHPC）的mTHPC@VES-g-CSO/TPGS-RGD纳米粒（RGD-NPs），以期增加mTHPC在肿瘤部位的积累，提高抗肿瘤光动力治疗效率。.本课题制备得到的RGD-NPs在水溶液中粒径~145 nm，Zeta电位~35 mV，由透射电镜及原子力显微镜观察可知RGD-NPs呈均匀球形；载药率为2.24 %；体外释放结果表明RGD-NPs具有一定的缓释效果；ROS产率检测得到RGD NPs的ROS量子产率（ΦΔ）为 0.36，与游离mTHPC的ROS量子产率相差不大（ΦΔ=0.43），说明包载后mTHPC依旧具有较好的ROS产生能力，可用于肿瘤光动力治疗。RGD-NPs在细胞水平的ROS检测实验结果显示，mTHPC包载于该混合胶束后在细胞中仍可有效地产生单线态氧；共聚焦显微镜观察细胞摄取结果显示，相较于游离mTHPC及无RGD修饰的NPs，U87MG 细胞能够摄取更多的RGD-NPs；MTT实验结果表明，在光照情况下，RGD-NPs的细胞毒性（IC50=0.27 μg/mL）明显高于游离mTHPC和无RGD修饰的NPs（IC50分别为8.35及3.11 μg/mL）；细胞凋亡检测结果显示RGD-NPs能够诱导细胞更多地发生凋亡；RGD-NPs还能够渗透进入U87MG肿瘤球内，具有较强的抑制肿瘤球生长的能力。采用活体成像仪考察RGD-NPs在皮下荷U87MG瘤裸鼠体内的分布情况，结果显示RGD-NPs能够更多地分布于肿瘤组织；皮下荷瘤裸鼠模型考察RGD-NPs的体内抗肿瘤疗效，抑瘤实验及组织病理学切片分析证实RGD-NPs具有更强的抗肿瘤光动力疗效；体重变化曲线及主要脏器组织切片结果显示RGD-NPs毒性较小，具有较高的安全性。.因此，本课题制备得到的RGD-NPs是一种具有良好主动靶向性及抗肿瘤光动力疗效的纳米给药系统，将为载光敏剂纳米给药系统在抗肿瘤光动力治疗领域的应用奠定了良好的实验基础。