基于深部肿瘤渗透的新策略高效构建肿瘤靶向治疗的仿生纳米细胞传递系统

The combination of traditional chemotherapy with anti-angiogenesis agents that inhibit blood vessel growth is an effective treatment for cancer. However, the implementation of this strategy has faced several obstacles such as chemotherapy agents of low concentration due to the inhibition of blood vessel growth by anti-angiogenesis agents, drug penetration obstacles from tumor micro-environment, and over-expression of hypoxia-inducible factor-1a (HIF1-a) correlated with increased tumor invasiveness and resistance to chemotherapy. Herein, we aim to develop a platform technology that can solve the challenges in deep tumor therapy. We report the sequential intra-intercellular nanoparticle delivery system drug delivery system, a ‘nanocell’, which is capable of a reversible swelling-shrinking in response to pH variation. The nanocell is composed of a nuclear nanoparticle capped with an extranuclear pegylated-lipid envelope. The outer membrane of the nanocell is decorated with ‘Marker of self’peptide and tumor-targeting peptide. The nano-nucleus is provided with the capability of lysosome escape and intercellular transfer. The nanocell enables a temporal release of two drugs: the outer envelope first releases an anti-angiogenesis agent, causing a vascular rupture; the inner nanoparticle, which is trapped inside the tumor, then releases a chemotherapy agent. The pH-sensitivity, optical properties, drug-loading efficiency and in vitro stability will be improved by optimizing the feed ratios, the coupling efficiency and drug loading method. Based on the complete bio-evaluation of the nanocomposites including tumor cell affinity, endocytosis, immune escape, lysosome escape, cytotoxicity and progressive drug release, the application of the nano-composites in real time tracing, their tumor-targeting ability and deep tumor penetration performance will also be evaluated. Furthermore, the coordinate anti-cancer activity of the nanocell will be estimated qualitatively and quantitatively both at cell level and animal level, and the immunohistochemical analysis will be carried out on different treated groups, which will facilitate elucidating the anti-cancer mechanism of the nanocell. The implementation of the project will provide a new strategy for developing deep tumor therapy and also provide a new way to solve the problems in the combination of traditional chemotherapy with anti-angiogenesis agents.

化疗与抗肿瘤血管生成剂联用这一新途径面临药物有效浓度低、药物渗透受阻、缺氧诱导因子表达高等难点。本课题拟结合纳米技术，从“递进式”渗透给药模式出发，探讨高效抑制肿瘤血管后充分输送化疗药物至肿瘤细胞，最终实现肿瘤深部有效治疗的新策略。我们将构建一种由纳米外膜和纳米核构成的药物传递系统—“纳米细胞”；外膜上偶联免疫“通行证”分子及肿瘤识别肽,纳米核具有溶酶体逃逸及细胞间转移能力，考布他汀、阿霉素及探针分别包覆于脂膜及纳米核中。在优化聚合比例、偶联效率及载药方法等基础上对仿生纳米细胞体系进行完整生物学评价，在位考察其肿瘤靶向特性，评价其肿瘤深度递送能力。进一步，利用三维共培养体系及荷瘤鼠模型考察其协同抗肿瘤活性（定性、定量），并对各给药组进行免疫组化分析，最终力求阐明该纳米细胞抗肿瘤机制。该课题的实现将为开发肿瘤深部有效治疗提供新策略，也为解决传统化疗与抗血管药物联用难点提供新的解决途径。

常规化疗药物由于与健康组织的非特异性相互作用而引起全身性副作用，这显着阻碍了它们的耐受性和功效。将化疗药物包裹或夹嵌于类脂核中制成的给药系统越来越引起关注，其优点在于毒性低、生物可降解、避免免疫反应及药物被体内的酶分解破坏。基于以上纳米材料形成的纳米药物，由于它们在药物靶向传递、提高药物生物利用度、实时药物示踪以及阐释药物作用机制等方面具有其他生化药物无可比拟的优势，已成为现代药物发展的重要趋势之一。 近年来，“被动靶向”已被广泛用作靶向肿瘤治疗，其利用增强的渗透保留效应。然而，这种依赖增强的渗透保留效应的方法与肿瘤血管形成的程度密切相关，这限制了其对许多肿瘤类型的功效。基于目前的现状和研究背景，本项目设计并研究了一种新型的药物传递系统——近红外光触发的智能纳米载药系统；由PEG及卵磷脂共聚物形成的纳米尺寸外膜，由两种天然脂肪酸结合得到PCM“核”纳米粒。外膜上偶联CD47及环状RGD肽分别实现对免疫系统的“逃逸”及对肿瘤的特异性识别；纳米粒子在环状RGD多肽的帮助下快速到达肿瘤部位并进一步将纳米粒圈定在肿瘤内部。近红外光吸收染料MBA和化疗药物阿霉素（DOX）上载于核纳米粒中。在近红外光的照射下，MBA吸收近红外光并转化为热能， 温度上升至PCM从固态变为液态，纳米粒子释放DOX进入核内，最终实现肿瘤深部治疗。在此基础之上，项目组还通过该温敏材料包覆硫化铜构建纳米载药系统，利用近红外荧光染料和抗癌药物实现对肿瘤的热疗与化疗相结合。本项目开发的新型药物递送系统对于癌症的诊断和治疗具有重要意义，有望通过仿生纳米载药系统和可视化癌症诊疗，来提高传统化疗与抗肿瘤药物联合治疗的效果，为解决传统化疗与抗血管药物联用难点提供新的解决途径。