基于透明质酸和硫酸米诺地尔协同克服血-肿瘤屏障的脑转移瘤靶向纳米粒的研究

It is a major challenge to achieve highly efficient chemotherapy for brain metastases. Overcoming the blood-tumor barrier (BTB) is considered as the key to solve the challenge. In this application, we propose to synthesize biodegradable poly(lysine)-b-poly(lactic-co-glycolic acid) copolymer as the basic carrier and then construct minoxidil sulfate and paclitaxel co-loaded nanoparticles (NPs) via the emulsion-solvent evaporation process. NPs are further modified by brain metastases-targeting hyaluronic acid which can efficiently cross the BTB using bi-functional a-Malemidyl-u-N-hydroxysuccinimidyl polyethyleneglycol. The final brain metastases-targeted NPs can synergistically overcome the BTB through the combination of hyaluronic acid and minoxidil sulfate. We hypothesize that 1) hyaluronic acid can render NPs the ability to cross BTB and actively target brain metastases; 2) minoxidil sulfate can open the BTB tight junctions and endow NPs with the ability to passively accumulate in brain metastases through paracellular pathway; 3) hyaluronic acid-mediated brain metastases-targeting and minoxidil sulfate’s slow release can improve the extent and duration of minoxidil sulfate-induced open of tight junction; 4) the passive accumulation through paracellular pathway by minoxidil sulfate can improve hyaluronic acid-mediated tumor cellular uptake of NPs; 5) the slowly-released paclitaxel can induce tumor cell apoptosis. The strategy proposed in this application can significantly enhance NPs' ability to overcome the BTB and accumulate in brain metastases. This project is of great theoretical significance and practical value for the exploration of highly-efficient and low toxic drug delivery systems to treat brain metastases.

脑转移瘤是肿瘤化疗领域的难点，解决问题的关键是克服血-肿瘤屏障(BTB)。本项目拟合成生物可降解的聚赖氨酸-聚乳酸-羟基乙酸共聚物作为载体，乳化-溶剂挥发法制备共载硫酸米诺地尔和紫杉醇的纳米粒；通过纳米粒表面氨基和双功能团聚乙二醇连接可跨BTB的脑转移瘤靶向配体透明质酸，构建透明质酸和硫酸米诺地尔协同克服BTB的脑转移瘤靶向纳米粒。本项目预期：①透明质酸介导纳米粒跨BTB主动靶向脑转移瘤；②硫酸米诺地尔打开BTB紧密连接，介导纳米粒通过旁路途径被动蓄积脑转移瘤；③透明质酸介导的脑转移瘤靶向和硫酸米诺地尔的缓慢释放可增效对BTB通透性提高的效应程度和时间；④硫酸米诺地尔介导的脑转移瘤被动蓄积可增效透明质酸介导的转移瘤细胞对纳米粒的摄取；⑤紫杉醇缓慢释放，诱导肿瘤细胞凋亡。本项目拟设计策略可有效提高纳米粒克服BTB和蓄积脑转移瘤的效率；对探索高效低毒的抗脑转移瘤制剂具有重要理论意义和实用价值。

脑转移瘤是肿瘤化疗领域的难点，解决问题的关键是克服血脑屏障（Blood-brain barrier, BBB）和血-脑肿瘤屏障（Blood-brain tumor barrier, BBTB）。本项目合成了生物可降解的聚赖氨酸-聚乳酸-羟基乙酸共聚物作为载体并以此制备了4种可渗透BBB或BBTB的脑转移瘤靶向纳米粒。①载米诺地尔和阿霉素、表面修饰聚乙二醇和CD44靶向配体透明质酸的脑转移瘤靶向纳米粒，可通过激活和强化乳腺癌脑转移瘤BBTB上特异性表达的ATP敏感钾离子泵，打开BBTB紧密连接，促进纳米粒本身在BBTB内皮细胞和脑转移瘤细胞上的摄取，通过“增强的”跨细胞途经和细胞旁路途经渗透BBTB，靶向乳腺癌脑转移瘤。②基于乳腺癌脑转移瘤血管内皮细胞上特异性表达具有内吞功能的前列腺特异性膜抗原（Prostate-specific membrane antigen, PSMA）这一临床发现，我们证实了转移性乳腺癌细胞可诱导脑微血管内皮细胞表达PSMA和P32；载阿霉素或拉帕替尼、PSMA和P32双靶向纳米粒可特异性渗透乳腺癌脑转移瘤BBTB并靶向脑转移瘤细胞上高表达的P32，介导脑转移瘤药物治疗。③载辛伐他汀和阿霉素、表面修饰聚乙二醇和低密度脂蛋白受体相关蛋白1（low-density lipoprotein receptor-related protein 1, LRP1）靶向配体Angiopep-2的脑转移瘤靶向纳米粒，可通过上调脑微血管内皮细胞和脑转移瘤细胞上LRP1，通过“增强的”跨细胞途径渗透BBB，靶向浸润性多病灶的早期脑转移瘤。④基于基底侧LRP1具有清除脑代谢物的天然功能，设计了HER2靶向肽—MMP1敏感肽—Angiopep-2融合多肽，融合多肽修饰的纳米粒，在乳腺癌脑转移瘤区域可响应微环境中MMP1脱落Angiopep-2，逃避基底侧LRP1介导的清除，提高在转移瘤区域的蓄积。本项目区别于常规脑肿瘤递药，形成了基于脑肿瘤BBB转运演变、内源性调控机制、脑肿瘤局部微环境的“可逆性”递药调控策略，并首次提出逃逸脑清除通路来提高药物脑内蓄积，可望广泛应用于脑疾病药物递送。本项目可有效提高纳米粒克服脑屏障和蓄积脑转移瘤的效率；对探索高效低毒的抗脑转移瘤制剂具有重要理论意义和实用价值。