基于凝胶多糖的多功能细胞支架的设计及其抗肿瘤免疫治疗活性的研究

Immunotherapy is one of the most effective anticancer approaches in clinic, of which the adaptive cancer therapy is the most promising one. However, systemically delivered therapeutic T cells suspension during ACT does not have tissue targeting ability, with short availability and transient persistence. In this project, we propose a novel implantable scaffold that simultaneously holds dendritic cells and T cells, and promotes persistent T cell differentiation and releases, therefore maximizing the anticancer effect of killer T cells. We will design a novel cell scaffold based on porous curdlan gel which provides a ligand for DC cell surface receptor Denctin-1, whose activation results in the differentiation of the DC and releasing of various cytokines. Then T cells loaded to the scaffold receive the stimulation from DC and differentiate into either cytotoxic CD8+ T cells or CD4+ helper T cells, which secrete from the scaffold and induce apoptosis in the neighboring tumor tissue. The success of our study would be an excellent theoretical guidance for the design of anticancer biomaterials, and would provide new insights into the development of T cell based anticancer immunotherapy.

免疫疗法是临床治疗肿瘤的最佳方案之一，其中细胞过继转移疗法（ACT）最具潜力。然而，ACT治疗方案中采用的治疗性T细胞，系统传送后在体内缺乏靶向性、滞留时间短、持续分化和缓释能力低。本项目拟设计的植入型细胞支架，能够同时负载树突状细胞（DC）和T细胞，并能够持续促进T细胞的分化和缓释，能够最大限度的发挥肿瘤的T细胞免疫治疗效果。我们拟采用多孔性curdlan作为细胞支架，其特点是：curdlan是DC表面受体dectin-1的天然配体（ligand），因此支架本体能够促进DC通过dectin-1信号通路的分化和诱导并释放多种cytokines，进而促进支架内部共存的T细胞的有效分裂，并刺激和诱导T细胞向CD8+细胞毒性T细胞或者CD4+辅助T细胞的分化，达到抗肿瘤的作用。本研究若成功，将为设计和研发抗肿瘤生物材料提供很好的理论基础，也能够为新型T细胞治疗技术的开发提供新的思路。

免疫治疗是极具潜力的肿瘤治疗方法之一。本项目采用天然凝胶多糖，通过化学改性得到具有抗肿瘤免疫功能的高分子材料。在小鼠的黑色素瘤模型上，经部分氧化得到的PGA高分子发挥了显著的佐剂作用，刺激促进了DC细胞的成熟，增强了抗原递呈活性，促进了T细胞的增殖，产生了明显的抗肿瘤活性。以氨基化的阳离子凝胶多糖、天然凝胶多糖以及阴离子凝胶多糖作为基质，通过“三明治”式的片层结构设计，制备了三种体系的八种植入型细胞支架。系统测定支架的外部形貌、内部立体结构以及溶胀性能的结果显示，支架材料外部呈层孔片状，内部空间尺寸适合细胞负载，支架的溶胀率较低，适合组织植入。采用表达绿色荧光蛋白的细胞株，证明了细胞支架具有良好的细胞负载能力。此外，支架对DC细胞的增殖具有显著的促进作用，并有效刺激并激活DC细胞释放IL-12、TNFalpha、IL-1beta等重要的细胞因子。综上所述，本项目成功制备了具有免疫刺激功能的天然多糖型细胞支架，在执行期内发表了7篇第一标注的论文，6篇第二标注论文和1项中国专利。