集光动力治疗、化疗于一体的卟啉－聚己内酯纳米粒的设计及其多模式肿瘤靶向治疗策略研究

The combination of photodynamic therapy (PDT) and chemotherapy that can exploit synergistic effects arising from the action of two species with the goal to maximize the therapeutic efficacy has now attracked more and more attention. However, the synergistic effect are highly dependent on the co-accumulation of the photosensitizers and chemotherapeutics at the tumor foci. Nanotechnology-based delivery systems have emerged as a promising platform for the combination of PDT and chemotherapy, but still suffer from low co-loading capacity, poor encapsulating stability and the lack of tumor active targeting and deep penetration. In order to solve these problems, in this project, a new class photosensitizer (pyropheophorbide a，PPA)-conjugated biodegradable poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL)-based amphiphilic block copolymer is designed and synthesized. The chemical conjugation of PPA is expect to enable efficient loading of photosensitizer, which will also decrease the crystallinity of mPEG-b-PCL copolymer and increase its compatibility with chemotherapeutics, representing a promising strategy to overcome the co-loading issue for the combination of PDT and chemotherapy; iNGR, a tumor vasculature homing peptide, is functionalized to the PPA-PCL nanoparticles to improve its tumor targeting and penetration efficiency. The multi-modal photodynamic and chemotherapy cancer treatment activities of the developed formulation and the mechanism of synergistic action will be investigated both in vitro and in vivo. The mechanism of how iNGR modification facilitate tumor targeting and penetration will also be disclosed. We believe this work will open a novel avenue towards the design of multi-modal nanocarriers for targeting cancer therapy.

光动力学治疗和化疗药物联合应用因能从不同机制高效杀灭肿瘤细胞、提高治疗效果而受到瞩目，但两者协同效应的发挥极大地依赖于光敏剂和化疗药物在肿瘤部位的有效共蓄积。纳米技术为整合光动力治疗和化疗于一体发挥协同作用提供可能，但仍存在两者共同包载的载药量低、稳定性差、载体安全性及系统缺乏主动靶向性和肿瘤组织穿透性等问题。本研究在原有基础上，设计了一种可生物降解的功能化聚己内酯材料与光敏剂偶联的纳米递释系统，解决了同时高效包载光敏剂和化疗药物的问题，并能增加纳米粒内核与化疗药物的相容性，表现出更高的载药能力和稳定性；并采用具有高效肿瘤血管靶向性和穿透能力的iNGR肽修饰该系统。通过体内外模型研究包载化疗药物的嵌合光敏剂纳米系统的多模式治疗特性及光动力治疗、化疗协同作用机制，并探讨iNGR修饰后系统的主动靶向特性和促肿瘤渗透机制。该多模式治疗系统的构建模式及相关研究国内外未见报道, 具有较高创新意义。

光动力学治疗和化疗药物联合应用因能从不同机制高效杀灭肿瘤细胞、提高治疗效果而受到瞩目，但两者协同作用的发挥极大地依赖于光敏剂和化疗药物在肿瘤部位的有效共蓄积。纳米技术为整合光动力治疗和化疗于一体从而发挥协同作用提供可能，但仍存在两者共同包载的载药量低、稳定性差及系统缺乏主动靶向性和肿瘤组织穿透等问题。本研究设计了两种可生物降解的功能化材料与光敏剂偶联的纳米递释系统：（1）以末端羟基化的聚乳酸-聚乙二醇-聚乳酸（HO-PLA-PEG-PLA-OH）为载体材料，通过酯化反应在其两端共价连接光敏剂焦脱镁叶绿酸a（PPa）；以该载体通过乳化溶媒蒸发法制备包载紫杉醇的双载药纳米递释系统。（2）通过开环聚合法合成载体材料聚乳酸-聚乙二醇-维生素E琥珀酸酯（TPGS-PLA），通过酯化反应合成光敏剂Ce6与聚乙二醇维生素E琥珀酸酯的键合物（TPGS-Ce6），采用纳米沉淀法制备共载Ce6与阿霉素的TPGS-PLA纳米粒。为进一步提高上述递释系统的肿瘤靶向性及肿瘤组织穿透能力，将肿瘤渗透肽修饰于递药系统表面。研究结果表明，上述策略均能制得载药量、包封率高且体内外性质稳定的纳米制剂。细胞水平实验显示，上述纳米制剂在光照条件下具有产生高水平单线态氧的能力，且能有效抑制耐药细胞P糖蛋白外排，从而具有更显著的诱导肿瘤细胞凋亡和抗增殖能力；多肽修饰后的纳米制剂具有更高的摄取量。荷耐药肿瘤的动物体内分布及肿瘤组织冰冻切片实验表明，该策略能使光敏剂和化疗药物在肿瘤部位有着较高的共蓄积，多肽的修饰能显著提高其靶向性并提高肿瘤实质的穿透能力。体内药效学实验结果表明，联合治疗策略能够有效提高耐药肿瘤的治疗效果，显著延长荷瘤小鼠的中位生存期，多肽的修饰使疗效得到进一步提升且具有良好安全性。该多模式治疗系统的构建模式及相关研究国内外未见报道, 为多药耐药肿瘤的治疗提供了新的治疗方案和实验依据，具有较高创新意义。