联合化疗、光热疗和免疫疗法的多功能聚合物纳米囊泡的构建及其用于肿瘤可视化治疗研究

Tumor therapy encounters several problems such as relapse due to the minimal residual disease, severe side effects of chemotherapy and lack of real time therapeutic monitoring. This project aims to develop a redox sensitive multifunctional polymersome that integrates tumor targeting,controlled drug release, and real time imaging within a single platform with a redox sensitive Y-shaped amphiphilic polymer for tumor imaging and combined chemo-photothermal therapy and immunotherapy. The polymersome can effectively deliver antitumor drugs (doxorubicin, DOX), near-infrared dyes(Cypate) and immunomodulatory agents ( imiquimod, IMQ ) into the tumor cells through enhanced permeability and retention (EPR) effect and active folate-targeting, where rapid release of the therapeutic cargo is triggered in response to high GSH condition inside the tumor cell. Cypate possesses functions of photothermal conversion and near-infrared fluorescent, thereby achieving photothermal therapy as well as non-invasive, real-time monitoring of polymersomes delivery, tissue distribution and the antitumor efficacy. Beyond the cytotoxic properties, DOX has the ability to induce immunogenic cell death to release tumor antigens and damage associated molecular patterns( DAMPs) that stimulate dendritic cells (DCs) maturation and activation with cooperation of IMQ in tumor microenvironment. The active DCs subsequently present antigen to T cells in the tumor draining lymph node resulting in tumor antigen specific activation of T cells that contribute to tumor rejection. This strategy represent a promising technology for combined chemo-photothermal therapy and immunotherapy to enhance the efficacy against tumor relapse.

针对肿瘤治疗中存在的不能杀灭所有肿瘤细胞而易复发、化疗毒副作用大、缺乏对疗效的实时监测等难题。本项目以还原敏感性Y型两亲性共聚物为载体材料，构建一种集分子靶向、环境响应性释药、实时成像为一体的多功能聚合物纳米囊泡，实现对肿瘤的可视化化疗联合光热疗和免疫疗法。纳米囊泡同时负载化疗药DOX、近红外染料Cypate和免疫调节剂IMQ，依靠EPR效应和叶酸主动靶向将其递送到肿瘤细胞内，并在细胞内高GSH环境中触发快速释药。利用Cypate具有光热效应和近红外荧光的特性，实现对肿瘤的光热疗及通过荧光成像实时、无创地监测纳米囊泡的体内递送、组织分布及抗肿瘤疗效。DOX直接杀灭肿瘤细胞的同时还引起肿瘤细胞免疫原性死亡，释放肿瘤抗原及损伤相关模式分子，在IMQ的协同作用下，诱导肿瘤微环境中幼稚DCs成熟、激活，呈递抗原，刺激T细胞活化特异性杀灭肿瘤细胞，彻底清除残留肿瘤细胞和微小病灶，控制复发。

目前，肿瘤仍然是死亡率较高的疾病。对于进展期和转移的肿瘤，化疗是主要治疗手段之一，但是由于化疗药物对肿瘤细胞缺乏选择性，导致其在正常组织器官中蓄积，产生严重的毒副作用，因此如何提高药物的靶向性，实现药物在肿瘤局部的控释和缓释，减少药物对正常组织器官的影响，高效、低毒抗肿瘤是肿瘤治疗领域的研究热点与难点。本项目首先设计合成了肿瘤微环境敏感性共聚物mPEG-SS-(PCL)2作为制备聚合物囊泡的载体材料，制备叶酸靶向聚合物囊泡，负载抗肿瘤药物阿霉素、血管生成抑制剂康普瑞汀和近红外荧光分子Cypate，依靠EPR介导的被动靶向和叶酸介导的主动靶向作用，将不同作用机制的药物递送到肿瘤局部，降低毒性，并实现对肿瘤的联合治疗。本项目合成了不同分子量和亲疏水嵌段比例的两亲性mPEG-SS-(PCL)2共聚物，考察了聚合物的分子量及嵌段比例对囊泡形成的影响，并以分子量1万、亲疏水嵌段比例为1:2的聚合物构建出具有典型结构的聚合物囊泡，在其表面修饰叶酸靶向分子，同时负载阿霉素、康普瑞汀和Cypate，考察了多功能囊泡还原敏感性释药行为，并研究了其体内示踪和体内外抑瘤效果。结果表明，制备的多功能聚合物囊泡具有肿瘤组织微环境还原敏感性快速释药特性，可有效促进肿瘤细胞的摄取及药物的快速释放，实现了不同作用机制的药物协同抗肿瘤作用，并且依靠示踪分子Cypate实现对疗效的实时监测。本项目的研究成果为应用聚合物囊泡实现高效、低毒的肿瘤治疗提供了依据。在项目执行期间，项目组已在Int. J. Nanomed.、Colloid Surface B等杂志发表SCI论文3篇。