以激活型肝星状细胞为靶向的MRI可视化的药物和基因联合输送治疗肝纤维化的研究

To date, there is no effective treatment for liver fibrosis. Activated hepatic stellate cell (aHSC) plays an essential role in the pathogenesis and progression of liver fibrosis.Therefore, induction of aHSC apoptosis is a potential therapeutic approach for liver fibrosis. In this project, multifunctional nano-micelle, which has the properties of efficient targeting and long circulation, will be loaded with drugs/siRNA and MRI constract for the targeted therapy and MRI monitoring of aHSC. Firstly, Integrin αvβ3 receptor, which is upregulated specifically on aHSC, is selected as therapeutic target. cRGD2, the specific ligand for integrin αvβ3, will be conjugated to the nano-micelle for aHSC targeting.Furthermore, the nano-micelle will be designed to be PH sensitive. Because of this property,drug leakage can be avoided in the process of transportation, wherease a burst release of drug can be triggered upon the entrance of nano-micelle into cells. Therefore, the release of pro-apoptosis drug doxorubicin (DOX) and siRNA of apoptosis resistance gene Bcl-2 could be controled intelligently. In addition, nano-micelle gets visible property through SPIO embeddedness. The distribtion and absorbance of drugs could be detected and the efficiency of targted therapy could be monitored through MRI molecular imaging. The project is expected to explore new approach to targeted therapy and monitoring of liver fibrosis through cross-diciplinary integration. The expected results of this project will have potential theoretical and applicable?significance.

目前尚无有效治疗肝纤维化的方法。激活型肝星状细胞（aHSC）是肝纤维化发生发展的中心环节，因此诱导aHSC凋亡是治疗肝纤维化的重要途径。本项目拟制备具有高效靶向性、长循环特点的新型多功能纳米胶束载体，联合传输治疗药物/siRNA和MRI对比剂，实现对aHSC的靶向治疗及MRI监测。首先，在聚合物纳米胶束的壳表层结构中引入针对aHSC特异性高表达的整合素αvβ3受体的cRGD2，获得对aHSC的特异性富集和主动靶向输送；同时，通过载体的酸敏设计，使其在体内传输过程中药物不释放，进入细胞后则快速释放，智能控释促凋亡药物阿霉素（DOX）和凋亡障碍基因Bcl-2的siRNA；并且，通过在胶束内包埋SPIO，赋予纳米载体可视化特性，通过MRI分子影像方法，了解药物分布、吸收情况，监测靶向治疗效果。本研究通过多学科交叉融合，探讨肝纤维化靶向治疗及监测的新技术手段，具有较大的理论研究意义及潜在应用价值。

诱导激活型肝星状细胞（aHSC）凋亡是治疗肝纤维化的重要途径。本项目针对aHSC特异性高表达的整合素αvβ3受体，将配体分子RGD多肽修饰铁蛋白纳米笼，即为RGD-FRT，做为药物载体；体外细胞实验证实RGD-FRT能够特异靶向大鼠肝星状细胞；进一步使用RGD-FRT包裹药物阿霉素（Dox）和姜黄素（CUR），与游离的药物相比较，RGD-FRT-Dox和RGD-FRT-CUR能够更有效的抑制肝星状细胞的生长；将显像剂Gd-BOPTA包裹到RGD-FRT纳米笼空腔，即RGD-FRT-Gd-BOPTA，MR成像结果显示：RGD-FRT-Gd-BOPTA具有很好的T1成像能力。针对靶向分子整合素αvβ3受体，还构建了靶向基因输送及MR显像的高分子聚合物载体，即RGD-PEG-g-PEI-SPION/siRNA；N/P 比值达到2.5 时，载体能够完全负载siRNA；与对照载体PEG-g-PEI-SPION相比较，RGD-PEG-g-PEI-SPION能够更有效的传输siRNA 至靶细胞；体外和体内MR成像均证实了RGD-PEG-g-PEI-SPION对整合素αvβ3受体的特异靶向性。体内验证纳米药物对肝纤维化治疗作用的工作正在进行中。本项目探讨肝纤维化靶向治疗及监测的新技术手段，具有较大的理论研究意义及潜在的应用价值。