肿瘤细胞核多级靶向精准药物和基因传递的高分子纳米载体的构建

Precise delivery is very important for the therapeutic effects of genes and drugs, but this study in the cell nuclear targeting delivery is very rare and meets a great challenge so far. Based on our previous works, this foundation aims at developing cell nuclear targeting delivery systems with polymer materials of good biocompatibility. According to the requirements of nuclear transport for nanocarriers, our study will imply the dendrimer PAMAM, which could form a single-molecular micelle with a very small size. The PAMAM is a popular carrier for drugs and genes with many amine groups. With the amine groups modified by nuclear localization signal peptides (NLS) and carefully controlling of the size, the nanocarrier can effectively delivery into cell nuclei mediated by the recognition of NLS and the NPCs. Afterward, further modifying the nanocarriers with tumor targeting RGD peptide, gene delivery R8 peptide, tumor mild-acidity sensitive methylmaleic anhydride and negative charged hyaluronic acid for long circulation, the nanocarriers can combine nuclear targeting with long blood circulation, tumor targeting, tumor environment responsivity and gene delivery. So that the multifunctional nanodrugs could pass through the many obstacles of drug delivery and realize the “from begin to terminal” one-stop precise delivery, which is of great significance for making the most of the medicines and inhibiting the side effect.

精准传递对于提高药物和基因治疗效果具有重大意义，但是目前细胞核靶向传递环节的研究非常薄弱，同时也具有很大困难。本项目在前期研究的基础上，采用生物相容性良好的高分子材料，构建细胞核靶向的药物传递体系。课题立足细胞核靶向传递对载体尺寸的严格限制，采用可形成单分子胶束的树形聚合物PAMAM，PAMAM尺寸很小且广泛应用于药物传递和基因传递，经过核定位信号肽等功能基团的修饰和对尺寸的调控，利用核定位信号肽的介导实现高效的细胞核内靶向传递。在此基础上，对纳米载体进一步引入肿瘤主动靶向基团RGD肽和基因传递肽R8，并通过肿瘤微环境敏感的化学键连接促进体内长循环的透明质酸，赋予纳米药物血液长循环、环境敏感性和肿瘤靶向以及基因传递等多种功能，使纳米药物能够跨越生物体内传递的多重屏障，从而达到从给药到最终位点的一站式精准传递，充分发挥肿瘤治疗效果和降低毒副作用。

精准传递对于大多数药物和影像探针功能的发挥具有重大意义，而采用靶向型或环境敏感型纳米载体输送系统是精准传递的关键。药物在体内输送面临着多重屏障，如何跨越这些屏障，实现对肿瘤的精准识别、对药物的精准传递与智能控释，是纳米医学研究的重要科学问题。本项目在实施中，围绕肿瘤靶向性药物传递、靶向探针以及进一步的细胞核靶向纳米药物，研究了一系列具有肿瘤靶向性、细胞核靶向性、刺激响应性等功能的纳米粒子，用于抗肿瘤药物的精准传递以及肿瘤的精准识别诊断。本研究已按计划顺利完成：（1）分别研究了采用树形高分子聚酰胺-胺PAMAM和PEG-PAsp(BzA)为基础载体，进行细胞核靶向肽等功能化修饰，构建了肿瘤细胞核靶向传递的纳米药物载体；（2）构建肿瘤微环境pH和还原双重响应性聚合物载体，实现了肿瘤被动靶向的药物传递和控制释放；（3）构建靶向肽修饰的SPIO纳米探针，实现了脑胶质瘤的靶向识别和MRI精准影像诊断。这些纳米药物可实现主动或被动的肿瘤靶向性药物输送、细胞核靶向传递或脑胶质瘤的影像诊断，为发展精准传递的纳米药物打下一定基础。在项目执行期间，负责人在国际重要刊物上发表标注本项目资助的SCI论文4篇，包括2篇通讯作者论文，均为中科院二区及以上期刊，SCI影响因子大于5，申请发明专利2项；另有一篇相关综述文章刚刚接收，一篇相关研究论文在投稿送审后返修。协助指导多名博士/硕士研究生顺利毕业，多次参加国内重要学术会议做学术交流并访问境内外较高研究水平的实验室。