多功能聚合物纳米囊泡的构建及其用于肿瘤的可视化化疗联合免疫疗法

Traditional chemotherapy encounters several problems such as severe side effects, multi-drug resistance, and lack of treatment monitoring and poor-prognosis. The aim of this project is to develop redox-sensitive multifunctional polymersomes using a self-assembly strategy to achieve various functions including targeting, imaging, controlled release and chemo-immunotherapy. The multifunctional polymersomes can incorporate hydrophilic chemotherapeutics (Doxorubicin, DOX) and near-infrared fluorophores (indocyanine green, ICG) in the aqueous lumen, as well as hydrophobic chemotherapeutics (Paclitaxel, PTX) and immunomodulatory agent (imiquimod, IMQ) in the hydrophobic membrane. The polymersomes can effectively deliver chemotherapeutics with different anticancer-mechanism (PTX and DOX) to the same tumor cell through passive and active targeting, where the release of chemotherapeutics would be triggered in response to high GSH in the tumor cell, thus leading to effectively kill cancer cells and overcome MDR. In addition, the polymersomes enabled NIR fluorescence imaging to in situ monitor the delivery process, tumor accumulation, drug distribution, and treatment effect. Furthermore, PTX and DOX mediated cell death release tumor specific antigen and other damage associated molecular patterns (DAMPs). While antigen in taken up by antigen presenting cells (APCs) majorly DCs, DAMPs along with IMQ diffused from within the solid tumor induce massive proliferation and activation of DCs. The active DCs present antigen to T cells possibly in tumor draining lymph node leading to proliferation of tumor specific lymphocytes. Finally, the cytotoxic T cells, other innate immune system cells such as NK cells and DCs are recruited towards inflamed tumor environment where they lead to tumor cell killing. The multifunctional polymersomes represent a promising technology for the combined chemo-immunotherapy to significantly enhance the efficacy against resistant tumors.

本项目针对传统化疗毒副作用大、易产生MDR、缺乏疗效监测、预后差等难题，通过分子自组装构建一类集靶向、成像、可控释药、并可实现化疗联合免疫疗法的还原敏感性多功能聚合物纳米囊泡。纳米囊泡可同时在亲水内腔载亲水药物DOX及近红外荧光成像分子ICG、在疏水膜层载疏水药物PTX及免疫调节剂IMQ，并在囊泡表面连接靶向分子，通过EPR被动靶向和主动靶向将具有不同抗癌机制的药物同时靶向递送到同一肿瘤细胞内，并被触发迅速释药以实现对癌细胞的有效杀灭及克服MDR；通过ICG近红外荧光成像可视化囊泡在体内的递送过程及药物分布，对疗效进行实时监控；PTX与DOX通过诱导肿瘤细胞凋亡/免疫原性死亡而释放肿瘤特异性抗原和DAMPs，在IMQ的协同下有效刺激肿瘤微环境中幼稚DCs成熟、激活DCs并呈递抗原，激活T细胞而激发并维持有效的抗肿瘤免疫应答，彻底清除残留的肿瘤细胞和微小转移病灶，实现肿瘤的化疗联合免疫疗法。

本项目旨在通过分子自组装构建一类集靶向、成像、可控释药、并可实现化疗联合免疫疗法的还原敏感性多功能聚合物纳米囊泡。纳米囊泡可将具有不同抗癌机制的药物同时靶向递送到同一肿瘤细胞内，并被触发迅速释药以实现对癌细胞的有效杀灭及克服MDR；通过近红外荧光成像可视化囊泡在体内的递送过程及药物分布，对疗效进行实时监控；通过免疫激动剂的协同作用有效刺激肿瘤微环境中幼稚DCs成熟、激活DCs并呈递抗原，激活T细胞而激发并维持有效的抗肿瘤免疫应答，彻底清除残留的肿瘤细胞和微小转移病灶，实现肿瘤的联合治疗。具体研究成果如下：.1.成功地合成了还原敏感性的两亲性共聚物PCL-SS-PEG-SS-PCL，通过分子自组装制备出共载化疗药与MDR逆转剂的聚合物纳米囊泡，研究表明其可有效提高纳米粒的靶向性，增加耐药细胞对化疗药的摄取，避免了化疗药物被肿瘤细胞泵出，加强了对肿瘤细胞的杀伤能力，从而克服了肿瘤的多药耐药性。.2.成功制备了可用于肿瘤化疗联合光热治疗并可近红外荧光成像示踪的聚合物囊泡，其具有pH/温度双重响应性、良好的稳定性、载药能力以及较强的光热转换效率，可通过激光促进细胞对囊泡的摄取和药物释放，其介导的化疗联合光热治疗具有良好的抗肿瘤效果，能够显著降低药物的毒副作用并示踪药物在动物体内的分布。.3.成功构建了靶向共负载抗原和免疫激动剂的聚合物纳米囊泡于肿瘤的靶向免疫治疗。其具有良好的抗原提呈细胞靶向性，增加了树突状细胞表面标志及细胞因子的表达。在体内该靶向囊泡表现出更强的淋巴细胞活化能力、效应性T细胞的免疫反应、CD8+ T和CD4+ T细胞应答及记忆性T细胞免疫反应。预防性动物实验结果显示，该靶向囊泡能够延缓肿瘤的出现，具有更好的抑制肿瘤生长的效果，可用于肿瘤的免疫治疗。.本项目的研究成果将为多功能纳米药物载体克服MDR、增强疗效监测、降低毒副作用、实现恶性肿瘤的靶向联合治疗提供研究基础，同时在学术上为分子自组装聚合物纳米囊泡作为新型药物载体的研发提供思路。