生物肽标载磁性药物微粒对脑胶质瘤靶向治疗的应用基础研究

Glioma accounts for more than 40% brain tumors. Survival time of the patients does not exceed 1 year in more than 60% patients even after consecutive surgery, radiotherapy and chemotherapy. Chemotherapy has been playing little role in improving the survival of patients because the local drug concentration is very limited after general administration. To solve the problem, this research is to manufacture HIV-1 tat labeled magnetic drug nanoparticles and test their physical and chemical features. Fluorescence/confocal microscopy, cytotoxicity tests and flow cytometry are used to observe their endocytosis and biotoxicity against glioma. Afterwards radio-imaging, high performance liquid chromatography, survival analysis and histopathology analysis are performed to evaluate the improvement of the interstitial intra/extra-cellular drug concentration and survival of glioma-bearing rats. This research aims to elevate intra-glioma drug concentration by magnetic and biological targeting to prevent low local drug concentration after systematic administration and poor chemotherapeutic effects, in order to provide an efficient and safe method for glioma chemotherapy.

脑胶质瘤占颅内肿瘤的40%。即使接受手术联合放化疗的综合治疗，60%以上患者生存期不超过1年。几十年来化疗对于改善患者预后始终效果不佳，缘于全身注射药物后肿瘤局部无法达到有效杀伤浓度，这成为脑胶质瘤化疗中难以攻克的难题之一，长期无明显突破。针对这一问题，本研究拟制作HIV-1 tat跨膜肽标载磁性药物微粒，先检测其物理化学特性，之后利用荧光/共聚焦显微镜、细胞毒性试验和流式细胞技术观察其对胶质瘤的入胞作用和生物毒性，然后通过核素成像、高效液相色谱分析、生存分析和病理组织学方法，检测在外磁场靶向下磁性药物微粒对脑间质和肿瘤细胞内药物浓度的提高作用，以及对荷瘤大鼠生存期的影响。本项目拟联用磁靶向和生物靶向作用提高脑胶质瘤内的药物浓度，解决全身给药后脑胶质瘤内药物浓度过低、治疗效果差的问题，以期为脑胶质瘤的化疗提供一种高效安全的新方法。

脑胶质瘤化疗领域进展缓慢，主要原因归结为脑内血脑屏障的存在和药物在瘤区滞留时间过短造成的瘤区局部药物浓度很低。提高肿瘤局部的药物浓度不仅能够增强化疗效果，而且可以有效改善肿瘤耐药。我们首先制作用生物肽链tat标载的磁性载药纳米微粒，通过药物释放实验发现其可以持续释药15天以上，表明其具有缓释作用。细胞毒性实验表明，纳米药物能对胶质瘤细胞发挥细胞毒性作用，其细胞周期变化与所载药物造成的肿瘤细胞凋亡一致，表明纳米药物能通过释放药物来诱导肿瘤细胞凋亡。同时荧光显微镜检查提示，药物分子能透过细胞膜进入细胞质内，并随着tat浓度增大荧光强度增强。同时tat生物标载能提高药物在细胞内的浓度。在动物模型中，给大鼠静脉注射注射tat标载磁性纳米药物后脑内药物浓度较普通药物提高5-8倍，荷瘤大鼠生存期延长1倍。上述研究表明，tat标载磁性纳米药物能有效提高脑内及肿瘤内药物浓度，有效杀伤肿瘤。