肿瘤胞外pH微环境响应的去PEG化“配体包埋式”主动靶向透明质酸环糊精纳米粒的几个科学问题

Although a number of studies focused on the key factors involved in the “blood circulation times”, “biodistribution” and “cellular uptake” of tumor-microenvironment sensitive peg decorated “exposed-ligands” active targeting nanoparticles, few studies concentrated on the similar key factors associated with tumor extracellular pH environment-sensitive de-pegylation “ligand-buried” active targeting nanoparticles. Thus in this study, we intended to develop the tumor extracellular pH environment-sensitive de-pegylation coated “buried” hyaluronic acid (HA)-cyclodextrin nanoparticles with uniform scale, and to estabilish the relationships between “blood long circulation”, “biodistribution” and “cellular uptake” of nanoparticles and pegylation (peg length and peg density), hyaluronic acid(molecular weight). And we focused on the effect of tumor environment sensitivity of de-pegylation on pharmacokinetics of the HA-based NPs, and highlighted the relationship between dynamic variation CD44 (clustering and re-presentation), molecular weight of hyaluronic acid and the activity of “cellular uptake”. Furthermore the key factors associated with the “blood circulation times”, “biodistribution” and “cellular uptake” of nanoparticles were estimated to optimize formulations of nanoparticles, to screen the optimal tumor extracellular pH environment-sensitive de-pegylation ligand-buried hyaluronic acid cyclodextrin nanoparticles. And the results would facilitate the design tumor extracellular pH environment-sensitive de-pegylation decorated “buried-ligand” active targeting nanoparticles based on the natural ligands.

尽管许多研究对影响肿瘤微环境响应PEG修饰的“配体外露式”主动靶向纳米粒的“长循环”、“组织分布”和“细胞摄取”的关键因素进行了系统研究，但是肿瘤微环境响应去PEG化“配体包埋式”靶向纳米粒的相关科学问题的研究还比较缺乏。因此本课题拟构建尺度一致的胞外pH响应型去PEG化透明质酸环糊精纳米粒，建立该类型纳米粒构建中PEG长度、密度和透明质酸分子量与“长循环”、 “组织分布”、“细胞摄取”等之间的关系；并与pH非响应型纳米粒进行对比，解析PEG可断裂性对该类型纳米粒药动学的调控；探讨透明质酸分子量与CD44受体的动态变化(聚集和循环再分布等)之间的关系及对纳米粒“细胞摄取”的影响。本项目通过定性定量分析体外制剂与体内药动和药效学等关键指标，筛选出体循环长、靶向性好、药效佳的去PEG化“配体包埋式”靶向纳米粒。本研究成果对基于天然配体的肿瘤微环境响应的“配体包埋式”靶向制剂的研发具有指导意义。

针对天然配体透明质酸主动靶向纳米制剂经PEG修饰后，虽然解决了其受体分布广泛，体内分布不理想，循环时间短，靶向性差的问题，但存在严重阻碍纳米粒细胞内吞和胞内溶酶体逃逸的不足，本课题构建了肿瘤微环境pH响应型可断裂PEG化的透明质酸环糊精主动靶向纳米制剂。从透明质酸分子量方面(7,63,102 kDa)对该纳米药物传递系统进行优化，并全面系统地考察了肿瘤微环境pH响应型可断裂PEG化策略对PEG化透明质酸环糊精纳米给药系统的影响，研究结果表明，透明质酸分子量对透明质酸环糊精主动靶向纳米给药系统的靶向能力有所不同，其中分子量为63kDa的纳米制剂具有最好的靶向效率,通过进一步的机制研究表明一方面透明质酸环糊精纳米制剂的主动靶向能力随透明质酸分子量的增加有所增加；另一方面，纳米粒诱导的CD44受体聚集现象也随透明质酸分子量的增加而加剧，影响着纳米粒的摄取效率，这两方面影响的综合结果决定了纳米制剂的最终靶向效率。体内研究进一步表明，肿瘤微环境pH响应型可断裂PEG化策略提高了PEG化透明质酸环糊精纳米给药系统主动靶向，细胞摄取和溶酶体逃逸能力，进而显著提高了其抗肿瘤效果。截至到目前，我们已发表SCI论文12篇，培养了5名博士生和1名硕士生，另有2名博士在读，1名博士后入站沈阳药科大学，与计划书所预定发表研究论文5-8篇，其中SCI收载论文3-5篇，培养博士生1-2名，硕士生3-4名相比，超额完成了预期的研究目标，取得了较为丰富的研究成果。