基于Cathepsin X响应的抗慢性淋巴白血病主动靶向控释纳米给药系统的构建与评价

The project aims at designing and constructing actively targeted and controlled nanodrug-delivery-system for curing chronic lymphocytic leukemia.The polymeric prodrug amphipathic carboxymethyl chitosan-R-Gly-Gly-phe- nylalanine mustard can be prepared by means of the linking arms and enzyme recognition sites of peptide for the model drug phenylalanine mustard, which can be self-assembled into nanoparticles.Then the actively targeted nanodrug- delivery-system in size about 100nm can be given by the coupling Fab segments at anti CD38 capable of recognizing CLL cells and these nanoparticles.Based on special recognition on R-Gly-Gly peptide segments and catalytic hydrolysis mechanism by cathepsin X,the delivery system can be designed, which can not only prevent original drug's leak at circulation, but also finish responsive release inside target cells.The controlled release can also be done by modulating prodrug's structural parameters and nanoparticles' size. With the help of researching on constructing methods for system, stability of systemic circulation, targeting in vitro and vivo, and release mechanism and drug efficacy, and probing on the solution to common problems of high toxic side effect of chemotherapy and drug's seriously adverse response for CLL, the novel, efficient,and less toxic nano delivery system for controlled release of phenylalanine mustard can be supplied with the methodology and theoretical basis.

设计和构建一种抗慢性淋巴白血病的主动靶向控释纳米给药系统。即以苯丙氨酸氮芥为模型药物，R-Gly-Gly肽段为连接臂和酶识别位点，制备两亲性羧甲基壳聚糖-R-Gly-Gly-苯丙氨酸氮芥高分子前药，并自组装形成纳米颗粒；将识别病变细胞的抗CD38抗体Fab片段与纳米颗粒表面偶联，制备尺寸100nm左右的主动靶向纳米系统。该系统基于Cathepsin X酶对R-Gly-Gly肽段的特异性识别与催化水解机制进行设计，既可避免原药体循环中泄露，又可实现靶细胞内响应性释放；调控前药结构参数与纳米颗粒尺寸，还可控制药物释放。通过对系统构建方法、体循环稳定性、体外与体内靶向性、释药机制和药效进行研究，探索慢性淋巴细胞白血病化疗药物制剂毒副作用大和不良反应严重等共性问题的解决方法，为研制氨基氮芥类药物的高效与低毒新型控释靶向纳米给药系统提供方法学和理论依据。

该项目分别设计和构建了酶响应的用于抗白血病药物的多种纳米药物传递系统，使用的模型药物为可用于血液病等恶性肿瘤的治疗药物美法仑。构建的纳米药物传递系统由载体、连接臂和药物三部分组成，通过对不同的响应模式构建不同的传递结构单元，实现药物的可控靶向响应。本项目的创新点在于通过合成过程的设计得到结构稳定的纳米粒，从而尽量减少载药纳米粒在血液循环过程中的药物泄漏的同时，又可以响应特定环境释放药物；以粒径为指标，考察了纳米粒的合成工艺对纳米粒粒径的影响，通过投料比控制，制备粒径适宜的纳米粒；系统的考察了载药纳米粒在不同模拟液中的释药行为，表明载药纳米粒在模拟血液环境的介质中药物泄漏量较少，而在模拟癌细胞内环境的介质中快速且较完全的释放药物。. 本课题设计构建的敏感性纳米载药系统的设计与研究不仅显著地提高了药物溶解性，增加其生物利用度，并且可实现了肿瘤环境靶向作用，解决了抗肿瘤药物对正常组织细胞毒副作用大等问题。该系统在血液循环系统中保持稳定，而由于肿瘤细胞内含体以及溶酶体等细胞器中特殊的弱酸性环境能触发化学键迅速断裂，因而可实现药物在肿瘤部位的快速释放。这种响应型的纳米载药系统的研制将为难溶性抗癌药物传输提供新的思路，在实现药物控释方面具有广阔发展前景。