多疗法高效协同集成纳米传递系统的构建及其在肿瘤多耐药性逆转中的应用研究

Because multidrug resistance (MDR) always be induced by decreasing of drug concentration and cytotoxicity simultaneously, the current approachs aiming to single factor could not overcome MDR effectively. Due to intracellular concentration and cytotoxicity of chemotherapeutic agent can be improved significantly by hyperthermia, it suggests thermo-chemotherapy could be a potential treatment on reversion of multidrug resistance. However, the effect of MDR reversion always be limited by synergistic effect of hyperthermia and chemotherapy. In order to overcome MDR by thermo-chemotherapy efficiently, the research puts forward an intergated delivery nanosystem by integrating with magnetic thermal agent (magnetic nanoparticles), thermo-sensitive polymer and chemotherapeutic drugs. To enhance synergistic effect of magentic hyperthermia and chermotherapy, the performances of intergated delivery nanosystem, the magentic hyperthermia temperature and lower critical solution temperature (LCST) of thermo-sensitive polymer, have been adjusted to match the optimal thermal enhancement temperature of corresponding drug. Because magnetocaloric effect of magnetic nanoparticles in an external alternating magnetic field (AMF) can trigger thermo-sensitive “on-off” switch of thermo-sensitive polymer to release drug under its optimal thermal enhancement temperature. Therefore, the intergated delivery nanosystem can satisfy the necessary conditions of efficient thermo-chemotherapy simultaneously, including sufficient thermal dose and spatio-temporal synchronism of thermo-chemotherapy. As the intergated delivery nanosystem revealed an excellent potential on simultaneous increasing cytotoxicity and intracellular concentration of chemotherapeutic agents for total tumor eradication, it is likely to become a prospective select for reversion of MDR with great safety and efficacy.

由于肿瘤多耐药性是化疗药物浓度降低和毒性降低多因素作用的结果，因此针对单一因素的逆转方法很难起到良好的疗效。鉴于热疗能显著促进化疗药物的细胞吞噬，并增强药物的细胞毒性，这为逆转肿瘤多耐药性提供了新的解决方案。但是利用热疗-化疗联合逆转肿瘤多耐药性的有效性取决于两种疗法协同作用的程度。为有效逆转肿瘤多耐药性，本项目基于化疗药物热增敏特性，设计了一种可高效协同多种疗法的集成式纳米传递系统，即在利用温敏囊泡载体共载磁流体热疗剂和化疗药物的基础上，同时将整个系统的磁热升温温度和药物释放的临界温度与药物的最佳热增敏温度相匹配。由于在交变磁场作用下，该集成系统内部的高效磁热疗剂可原位放热，达到药物的最佳热增敏温度后触发药物的迅速释放。因此，该系统可同时满足热化-化疗高度协同的必要条件：充足的热疗、热疗-化疗作用空间和作用时间的同步性。因而该集成式纳米传递系统为肿瘤的耐药性逆转提供了一种新的选择和思路。

肿瘤耐药的发生是制约肿瘤临床化疗疗效的关键因素。为解决这一难题，我们利用温敏囊泡将具有极高磁热转换效率的疏水单分散磁性纳米颗粒与化疗药物共载，通过调节温敏载体的相变温度（LCST）实现化疗与磁热疗的高度协同作用，最终实现肿瘤耐药性的有效逆转。.首先我们制备了一种集成式囊泡型纳米载体，该载体不仅具有很好的稳定性和磁学性能，磁热转换能力（SAR值）高达1436.1 W/g。在优化的条件下，这种集成式囊泡型纳米载体介导的磁热疗可以有效地以诱导细胞凋亡的方式抑制肿瘤增殖。然后，我们以阿霉素（DOX）和顺铂为药物模型，分别构建了具有适当LCST的集成式囊泡型载体，并研究了这种载体系统在磁控药物释放、磁热疗增强药物细胞毒性以及利用磁热疗和化疗协同逆转肿瘤耐药性的潜能。研究发现，两种药物都可以通过磁热作用而发生急速释放。而肿瘤增殖抑制和肿瘤耐药性逆转研究发现，该集成式囊泡型载体系统介导的磁热疗-化疗的协同作用显著增强药物（DOX和顺铂）细胞毒性，并有效抑制相关耐药细胞增殖的能力。随后的机理研究发现，磁热疗做为一种高效的刺激手段，可以有效地促进药物的细胞内吞，特别是增加药物在细胞核内集中或与DNA结合。因此该集成式囊泡型载体系统介导的磁热疗-化疗的协同作用可有效增强药物的细胞毒性。而耐药相关基因的定量研究发现磁热疗可以有效抑制多种耐药相关基因的表达和活性。