具有低温光热和免疫治疗功能的高分子基因载体的制备及抗肿瘤治疗的研究

The occurrence and development of tumors are complicated processes. It is urgently demanded to develop multifunctional tumor treatment strategy with excellent performance in synergetic cancer therapy, since single treatment method is difficult to achieve the thorough tumor ablation. Gene carriers based on gold nanorods (AuNRs) are widely applied in tumor treatment due to their excellent characteristics including unique fluorescence property, photoacoustic imaging ability, photothermal conversion capacity and facile surface modification. However, the normal tissues and cells are inevitably damaged while the photothermal therapy is performed to kill cancer cells using AuNRs. Herein, the nanoplatform based on AuNRs as the cores and pH-responsive polyethylene glycol-polylysine-polyhexamethylenediamine methacrylate (PEG-PLys-PHMA) as the surface modification is designed for the first time. This platform would exhibit the advantages as followings: (1) AuNRs possesses photothermal therapy ability; (2) In the physiological environment, PHMA is hydrophobic and could load with anticancer drug (such as gambogic acid, etc.) that could contribute to the low-temperature photothermal therapy; in the acidic tumor environment, PHMA converts to be hydrophilic, and the drug release could be realized; (3) PLys-PHMA chain segment could load with the silence gene shPD-L1 that encoding programmed death ligand -1 (PD-L1), and could facilitate the attack of tumor cells by T cells, which result in the damage of residual and metastasis tumor cells. The nanoplatform that constructed in this project integrates photothermal therapy, gene therapy and immune-therapy, and is expected to synergistically ablate tumors thoroughly.

肿瘤的发生和发展过程复杂，单一疗法难以实现彻底治愈，亟需开发一种综合性能优异的多功能协同抗肿瘤治疗策略。金纳米棒（AuNRs）因其独特的光声、光热性能及表面易修饰等优点，已被广泛用于肿瘤治疗研究。但AuNRs光热治疗时，杀灭肿瘤细胞同时，还对正常的细胞组织具有杀伤作用。本项目首次提出以AuNRs为核心，表面修饰具有pH响应性的聚乙二醇-聚赖氨酸-聚六甲基烯亚胺甲基丙烯酸乙酯（PEG-PLys-PHMA）。该策略具有如下功能：（1）AuNRs光热治疗作用；（2）PHMA生理环境疏水，可担载有助低温光热的小分子药藤黄酸，肿瘤弱酸环境亲水，利于药物快速释放；（3）PLys-PHMA链段担载程序性死亡配体-1（PD-L1）沉默基因shPD-L1，促进杀伤性T细胞对肿瘤细胞的攻击，进一步杀伤残余和转移的肿瘤细胞。本项目所制备的载体体系集光热、基因和免疫治疗为一体，有望通过协同增效的作用来抑制肿瘤。

本项目针对抗肿瘤治疗中所遇到的肿瘤富集性差、纳米药体内循环多重屏障以及缺乏系统治疗方案等问题。创新将光热治疗与免疫治疗相结合。在课题的研究中，我们使用“原位疫苗”联合肿瘤温热治疗的方法。因为肿瘤特异性抗原会对肿瘤纳米疫苗的使用有所限制，因此我们需要采用原位疫苗联合肿瘤温热治疗的手段逆转肿瘤免疫抑制微环境，我们进一步联合肿瘤温热治疗，开发“原位首先，通过静电和疏水相互作用将化疗药米托蒽醌（MTO）和藤黄酸（GA）共载于聚乙二醇-g-聚（L-谷氨酸）（PLG-g-mPEG）高分子载体中，制备 MG@NPs 纳米药物。MTO 和 GA可以协同引起肿瘤免疫原性细胞死亡，被杀伤的肿瘤细胞作为“原位疫苗”激活机体免疫反应。进一步构建了卟啉基共价有机框架（COFs）纳米复合材料，以扩展卟啉基纳米材料的生物医学应用。共价有机框架材料在水溶液中分散性与水稳定性较差，阻碍了其进一步生物医学应用。为了解决此问题，我们通过菁类染料（IR783）与 COFs 组装制备了水分散的卟啉基共价有机框架纳米复合材料（COF@IR783） 。光热治疗作为一种新型的肿瘤治疗策略是将激光光能转化为热能，有针对性地在局部杀死癌细胞，因其在恶性肿瘤治疗方面的微创性和有效性而快速发展。热休克蛋白是一种在细菌和哺乳动物体内广泛存在的一类热应急蛋白。当生物体暴露于高温时会合成此种蛋白以保护自身。最后，为了更好的实现光热治疗与免疫治疗的结合，我们使用载体材料PEG-PLG担载具有光热性能的菁类染料IR783与藤黄酸协同作用产生低温光热的效果。通过抑制热休克蛋白的合成能够降低肿瘤细胞的耐热性，从而提升肿瘤光热治疗的效果和降低治疗所需要的温度。我们认为，免疫治疗与低温光热治疗结合的方法作为一种新型的肿瘤治疗策略可以对肿瘤进行有效抑制，可以更有针对性地在杀死实体肿瘤细胞和远端肿瘤。