Targeted saponin nanoparticles as a novel tool to enhance the efficacy of tumor-specific toxin therapy by pH dependent trigger

靶向皂苷纳米颗粒作为一种新工具，通过 pH 依赖性触发增强肿瘤特异性毒素治疗的功效

• 批准号: 228859562
• 负责人: Dr. Mayank Thakur, Ph.D.
• 金额: --
• 依托单位: Institut für Laboratoriumsmedizin, Klinische Chemie und Pathobiochemie (CVK)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/228859562?language=en
• 关键词: Targeted; saponin; nanoparticles; novel; tool

Saporin (Sap-3) based targeted toxins together with particular saponins (Spn) (glycosylated triterpenoids) is proven to have highly augmented, tumor cell specific toxic effects. This synergistic augmentation is found to be more than a million fold in vitro and specific to the tumor cell types. However, specificity is maintained by the targeted toxin while the saponins are widely distributed in the body. Therefore, dose finding and the application scheme of two different routes at different time intervals are major problems. A basic strategy to prepare target specific saponin nanoparticles is therefore warranted, from an in vivo perspective. It is envisaged to develop a bio-degradable nanocarrier which is able to deliver the saponin with or without toxin specifically to the tumor cell. These actively targeted nanoparticles would release the saponin and/or the targeted toxin in a pH dependent manner thus certifying a release inside the endo/lysosomes where the synergistic effect takes place and providing a sure-shot specific tumor cell toxicity. Salient features of the proposed project are as follows.a. The first novel objective is to prepare completely biodegradable and bio-compatible nanoparticles of saponins with proven toxicity enhancement effects. The toxin would be entrapped inside a matrix that would specifically carry the toxin to desired tumor site via ligand-receptor mediated targeting and both components would thus be delivered at the same time for synergistic augmentation of toxin efficacy. b. The second objective is the development of a pH sensitive core having a swelling (at endo/lysosomal pH)-shrinking (at cytosolic pH) core entrapping the toxicity enhancing saponins. The swelling of the shell at acidic pH of endo/lysosomes would lead to the target site-specific release of saponin from the core. The swelling shrinking behavior would be optimally adjusted via chemical modification to control the release pattern of saponins in the vicinity of the tumor to provide a sustained effect. c. A third approach would be to prepare EGFR targeted nanosized particles or vesicles using biocompatible polymer viz. double cross-linked pH sensitive chitosan. Saponins would be entrapped in the core of the chitosan matrix. This strategy would give the flexibility of choosing different natural polymers as basis for utilizing saponins in therapeutics thus reducing hemolytic and inflammatory effects. The prepared systems will be tested for selectivity and specificity to tumor cells in vitro. Most potent and stable systems would thereafter be tested in vivo in a BALB/c and nude mouse model. It is notable that the proposed system is highly flexible, the targeting moiety (EGF) can be replaced by a monoclonal antibody or another targeting domain, and the toxin can be replaced by other toxins or therapeutic modalities. pH dependent release would be a significant step ahead to mitigate the problems with the endosomal escape of therapeutic substances.

基于皂苷（Sap-3）的靶向毒素与特定皂苷（Spn）（糖基化三萜）一起被证明具有高度增强的肿瘤细胞特异性毒性作用。这种增效作用在体外被发现超过一百万倍，并且对肿瘤细胞类型有特异性。然而，当皂苷在体内广泛分布时，其特异性被靶向毒素所维持。因此，剂量的确定和两种不同途径在不同时间间隔的应用方案是主要问题。因此，从体内的角度来看，制备目标特异性皂苷纳米颗粒的基本策略是必要的。设想开发一种生物可降解的纳米载体，能够将皂素带或不带毒素特异性地递送到肿瘤细胞。这些活性靶向纳米颗粒将以pH依赖的方式释放皂苷和/或靶向毒素，从而证明在协同作用发生的内切酶/溶酶体内释放，并提供确定的特异性肿瘤细胞毒性。拟建项目的主要特点如下：第一个新目标是制备完全可生物降解和生物相容性纳米皂苷具有已证实的毒性增强作用。毒素将被包裹在基质中，基质将通过配体受体介导的靶向特异性地将毒素携带到所需的肿瘤部位，因此两种成分将同时被递送，以协同增强毒素的功效。b.第二个目标是开发一个pH敏感核心，该核心具有肿胀（在内端/溶酶体pH值处）-收缩（在细胞质pH值处），包裹着增强毒性的皂苷。内切酶/溶酶体在酸性pH下使外壳膨胀，导致皂素从核心释放到特定的目标位点。通过化学修饰控制肿瘤附近皂苷的释放模式，优化调节肿瘤的消肿行为，使其具有持久的效果。c.第三种方法是使用生物相容性聚合物（即双交联pH敏感壳聚糖）制备EGFR靶向纳米颗粒或囊泡。皂苷将被包裹在壳聚糖基质的核心中。这一策略将为选择不同的天然聚合物提供灵活性，作为在治疗中利用皂苷的基础，从而减少溶血和炎症作用。制备的系统将在体外测试对肿瘤细胞的选择性和特异性。此后，大多数有效和稳定的系统将在BALB/c和裸鼠模型中进行体内测试。值得注意的是，所提出的系统具有高度的灵活性，靶向部分（EGF）可以被单克隆抗体或其他靶向结构域取代，毒素可以被其他毒素或治疗方式取代。pH依赖性释放将是缓解治疗物质内体逃逸问题的重要一步。