一种新型肿瘤主动靶向治疗载体---P-糖蛋白高表达的间充质干细胞的研究

Mesenchymal stem cells (MSCs) have inherent tumor-tropic and migratory properties, which allows them to serve as vehicles for targeted drug delivery systems for isolated tumors and metastatic diseases. MSCs have been successfully studied and discussed as a vehicle for cancer gene therapy. However, MSCs have not yet been discussed adequately as a potential vehicle for traditional anticancer drugs. We found that the free drug amount and its local concentration in the cytoplasm of the MSCs were dramatically increased with the uptake of paclitaxel nanoparticles (PTX-NPs), which could cause the death or induce apoptosis of the MSCs. Although we have previously adopted MDR1 gene-transfected MSCs expressing P-glycoprotein (P-gp) to carry PTX-NPs and constructed a preliminary tumor-targeting drug delivery system, intensive studies should be performed to optimize this technique and understand its mechanism of action. In this project, three key processes, which are internalization of NPs, drug release and tumor tropism migratory dynamics of MDR-MSCs, will be studied through laser scanning confocal microscope, microdialysis, immunofluorescent labeling，Matlab software, etc. This project will lay the foundation for MDR-MSCs as a targeting delivery vehicle for anticancer drug-loaded nanoparticles.

间充质干细胞(MSCs)具有特异性地向肿瘤及炎症等病灶迁移的特性，以MSCs为主动靶向载体的治疗方案有望成为肿瘤治疗的新策略。然而目前该领域的研究主要局限于将其作为基因治疗的细胞载体，能否将MSCs发展成为适于抗肿瘤化学药物靶向治疗的载体呢？我们在前期工作中发现，如直接以MSCs包覆紫杉醇纳米粒，纳米粒释放出来的游离药物在细胞内蓄积，会损伤MSCs。项目组通过基因转染，使MSCs细胞膜高表达具有药物外排泵功能的P-糖蛋白，及时泵出游离药物分子，解决了上述难题，初步构建了一种能靶向肿瘤微环境并在局部缓释药物的长效主动靶向给药系统。本项目采用激光扫描共聚焦显微镜、微渗析、荧光标记、Matlab等技术，对该系统构建中载药、释药和靶向三个关键问题开展相关基础研究，为构建以MSCs为载体的抗肿瘤化学药物主动靶向给药系统奠定基础，探索肿瘤治疗的新策略。

间充质干细胞(MSCs)具有特异性地向肿瘤及炎症等病灶迁移的特性，然而目前该领域的研究主要局限于将其作为基因治疗的细胞载体，能否将MSCs发展成为适于抗肿瘤化学药物靶向治疗的载体呢？我们在前期工作中发现，如直接以MSCs包覆紫杉醇纳米粒，纳米粒释放出来的游离药物在细胞内蓄积，会损伤MSCs。项目组通过基因转染，使MSCs细胞膜高表达具有药物外排泵功能的P-糖蛋白，及时泵出游离药物分子，解决了上述难题，初步构建了一种能靶向肿瘤微环境并在局部缓释药物的长效主动靶向给药系统。本项目采用激光扫描共聚焦显微镜、微渗析、荧光标记、Matlab等技术，对该系统构建中载药、释药和靶向三个关键问题开展相关基础研究，为构建以MSCs为载体的抗肿瘤化学药物主动靶向给药系统奠定基础，探索肿瘤治疗的新策略。.（1）.成功建立了Pgp-MSCs细胞株，并对其进行分选和表达、耐受性及因素测定，证明其符合标准。.（2）.乳化-溶剂挥发法成功制备PTX-NPs，最终处方制备的纳米粒平均粒径为142nm，PDI=0.102，符合要求；用扫描电镜和透射电镜测定其纳米粒的形态特征；并对纳米粒进行了体外累积释放。.（3）.成功建立了PTX-NPs-Pgp-MSCs给药系统，并对其PTX-NPs纳米粒的浓度、粒径、Zeta电位进行检测，并检测了Pgp-MSCs与纳米粒孵育时间及包覆效率。.（4）.采用微渗析取样技术，研究了PTX-NPs-Pgp-MSCs药物释放，其突释效应减小，释放时间延长。.（5）.建立人恶性胶质瘤裸鼠脑原位移植瘤模型，测定了Pgp-MSCs包覆含药纳米粒后的靶向动力学及体内药效学。靶向动力学研究表明，PTX-NPs-Pgp-MSCs具有良好的肿瘤靶向性，可显著降低PTX的毒副作用。