超声激发载氧相变纳米滴-携iRGD肽载药肝素纳米粒复合物克服肿瘤多药耐药及其机制的研究

It has been demonstrated in our previous experiments that ultrasound can increase the sensitivity of dual-ligand drug-loaded nanoparticles on MCF-7/Tax multidrug resistant breast cancer cells, but it needs to be improved according to the characteristic of tumor microenvironment for better application in vivo. Multidrug resistance (MDR) is an important reason for the failure of chemotherapy. Since hypoxic microenvironment in tumor contributes to MDR and malignant tumor progressing, it may improve the reaction to chemotherapy by increasing oxygen in tumor tissue thereby overcoming MDR. Perfluorocarbon (PFC) is a good oxygen carrier with a poor dispersion in blood and high solubility to oxygen. Oxygen combined with PFC to prepare oxygen-loaded microbubbles can deliver oxygen to tumor tissue and image at the same time assisted by ultrasound. It is an effective strategy to reduce chemotherapy resistance in tumor, however, the oxygen carried in microbubbles is limited and not enough to facilitate tumor therapy. Previous research have shown that liquid PFC not only exerts a high oxygen carrying capability and good stability, but also releases oxygen well and displays a good ultrasound imaging after liquid-gas phase transition. Here, we will prepare a complex composed of oxygen-loaded phase-change nanodroplets and iRGD-drug-loaded heparin nanoparticles through avidin-biotin linkage. The phase change of the complex and its release of oxygen and free drug assisted by ultrasound will be investigated. Importantly, we try to explore the mechanism of complex in improving tumor chemotherapy and overcoming multidrug resistance attributed to high level of oxygen delivery, constructing a novel drug delivering system with high chemotherapeutic drug carrying capability and good potential for ultrasound molecular imaging.

我们已证实超声辐照可增加双配体载药纳米粒对乳腺癌耐药细胞MCF-7/Tax的敏感性，但体内应用需针对肿瘤环境进行改进。多药耐药是化疗失败的重要原因，乏氧微环境是肿瘤产生多药耐药和恶性进展的促成因素，通过氧供改善乏氧微环境可能改善治疗的反应性，进而对抗多药耐药。全氟碳化合物（Perfluorocarbon，PFC）在血液中弥散性差、对氧气溶解能力高，是较好的氧气载体。将氧气和气态PFC混合构建载氧微泡，在超声显像同时超声辐照爆破微泡，将氧气递送到肿瘤组织，是改善化疗抵抗的策略，但微泡到达肿瘤时氧含量难以维持较高水平。利用液态PFC携氧能力强，稳定性好，释氧充分且液气相变后显像好的特点，我们制备载氧相变纳米滴-携iRGD肽载药肝素纳米粒复合物，通过超声干预促进复合物相变及释氧、释药，研究氧气释放对肿瘤化疗及耐药性能的改善作用及机制，构建一种兼具高效药物运载及分子显像潜能的新型载药系统

肿瘤耐药是肿瘤治疗失败的重要原因，乏氧微环境是肿瘤产生多药耐药和恶性进展的促成因素，通过氧供改善乏氧微环境可能改善治疗的反应性，进而对抗多药耐药。首先我们利用全氟碳化合物（Perfluorocarbon，PFC）氧气溶解能力高、生物相容性好的特性，采用乳化-均质法制备了载氧氟碳纳米液滴（Oxygen-carrying Nanodroplets，O2-NDs），通过超声辐照干预促进复合物相变及释氧，进而研究改善乏氧对肿瘤化疗及耐药性能的影响及机制，初步在体内取得了较好的逆转化疗耐药的效果。放疗作为肿瘤治疗的主要手段之一，乏氧是造成肿瘤放疗抵抗的重要原因，课题组进一步尝试探讨改善和调节肿瘤乏氧微环境后对肿瘤放疗敏感性的影响：利用纳米构建技术主要从两个方面着手改善肿瘤乏氧并探讨放疗增敏情况，一是构建超小金纳米簇原位催化肿瘤内高过氧化氢（H2O2）生成氧气（O2），从而改善肿瘤乏氧，同时携带ICG及利用金纳米团簇的高Z元素性能对肿瘤进行光动力及放疗协同治疗；二是构建结合硫化铜的介孔钽纳米颗粒载含氧相变氟碳（CPTC@PFP@O2）通过EPR效应聚集于肿瘤局部，利用CPTC@PFP@O2表面吸附CuS颗粒的良好光热性能，通过激光辐照产热使氟碳液滴相变释氧，改善肿瘤乏氧环境，利用钽元素的高Z元素性能，对肿瘤进行放疗治疗。上述研究工作体内外结果均表明改善肿瘤乏氧后，会明显提高肿瘤对放疗乃至光动力治疗的敏感性，表明改善肿瘤乏氧微环境会明显增敏肿瘤放化疗等治疗效果，改善肿瘤治疗耐受性，从而抑制肿瘤恶性进展。