基于温度/pH敏感纳米凝胶亲疏水性反转策略调控抗肿瘤药物体内过程研究

To solve the "PEG dilemma" and "EPR controversy" in the biofate of antineoplastic nanomedicine, this project focuses on two key scientific problems: ① How does the hydrophilic-hydrophobic reversal coordinate the contradiction between long circulation and cellular uptake of temperature/pH-sensitive nanogels on which our group had a solid foundation? ② How does the hydrophilic-hydrophobic reversal of temperature/pH-sensitive nanogels regulate the extravasation from tumor blood vessel and the intratumoral penetration? Therefore, the temperature/pH-sensitive nanogels with different lower critical solution temperatures (LCSTs) will be constructed. The effects of hydrophilic-hydrophobic reversal on the long-circulation of nanogels (including the opsonization of blood proteins and RES phagocytosis), the intratumoral penetration (including the extravasation from tumor blood vessel and penetration in the tumor stroma using in vitro models) and the cellular uptake of nanogels will be systematically investigated. Furthermore, the inhibitory effects of doxorubicin-loaded temperature/pH sensitive nanogels on the growth of liver cancer and their pharmacokinetics will be evaluated. This project elucidates the significance and influence patterns of hydrophilic-hydrophobic change of nanomedicine on its biofate, which will provide a novel strategy for developing a highly efficient tumor targeted nano drug delivery system.

针对目前抗肿瘤纳米药物体内过程中存在的"PEG困境"和对EPR效应的争议，以我们具有良好前期工作基础的温度/pH敏感纳米凝胶为模型纳米药物载体，聚焦纳米凝胶亲疏水性反转是如何协调其长循环特征和肿瘤细胞摄取行为、以及如何调控其血管外排和肿瘤组织穿透行为这两个关键科学问题，构建具有不同低临界会溶温度（LCST）的温度/pH敏感纳米凝胶，系统研究亲疏水性反转对纳米凝胶的血浆蛋白调理及RES细胞吞噬等长循环特性的影响，对模拟肿瘤血管外排和模拟肿瘤组织基质穿透性能的影响，以及对肿瘤细胞摄取行为和机制的影响等。结合载阿霉素温度/pH敏感纳米凝胶抑制小鼠原位肝癌生长的药效学和药物动力学评价，揭示纳米药物亲疏水性变化对其体内过程的影响规律及重要意义，为发展一类新型高效的肿瘤靶向纳米载药系统提供新思路。

如何解决体内长循环、被肿瘤细胞和肿瘤干细胞有效摄取、在肿瘤部位高效富集及深部穿透等对纳米载药系统特性需求的矛盾仍然是其面临的主要挑战。本项目构建了具有快速疏水反转的基于聚N-异丙基丙烯酰胺（pNIPAM）的温敏纳米凝胶载药系统，其在血液（pH 7.4、37 ℃）中是亲水的，有利于长循环；通过EPR效应到达肿瘤组织后，在肿瘤组织微酸性环境（ pH 6.5、37 ℃）下，纳米凝胶迅速反转成疏水性，有利于其在肿瘤组织高度富集、深部穿透及被肿瘤细胞和肿瘤干细胞有效摄取；通过内吞途径进入肿瘤细胞后在溶酶体酸性环境（pH 4.5）中，电荷反转成正电荷，有利于其逃逸溶酶体进入细胞质，并在细胞质高GSH条件下响应性释放抗肿瘤药物阿霉素。此纳米凝胶载药系统具有良好的抗肿瘤及杀伤肿瘤干细胞的作用，并有效改善阿霉素的不良反应。在此课题基础上，进一步构建了系列瘤内注射或介入栓塞的温敏纳米凝胶载药系统及基于羟乙基淀粉（HES）的纳米载药系统，实现对肿瘤的有效杀伤。此项目对设计更有效的纳米载药系统提供理论依据。