具不对称膜结构的pH敏感可降解智能型聚合物囊泡用于肿瘤高效靶向治疗

In this project, we set to design endosomal pH responsive chimaeric polymersomes for high efficient loading of water soluble drugs e.g. siRNA and/or water insoluble anticancer drugs (e.g. paclitaxel and doxorubicin) for targeted cancer therapy. The polymersomes with asymmetric membranes are composed of polyethylene glycol-b-poly(2,4,6-trimethoxybenzilidene -tri(hydroxymethyl)ethane methacrylate)-b-polyelectrolyte (PEG-PTTMA-PI) triblock copolymers. The polyelectrolyte block includes the cationic poly(dimethylaminoethyl methacrylate) (PDMA), poly(diisopropylaminoethyl methacrylate) (PDPA) and poly(histamine acrylamide) (PHA), and anionic poly(methacrylic acid) (PMA) and poly(acrylic acid) (PAA) under physiological conditions. Via electrostatic interaction the polymersomes with cationic polyelectrolyte inner shell can encapsulate anionic drugs like siRNA and methotrexate with high efficiency, and those with anionic polyelectrolyte inner shell can encapsulate cationic drugs like doxorubicin hydrochloride with high efficiency. The hydrophobic membrane cores not only serve as harbor for hydrophobic anticancer drugs but also present as physical barrier better protecting biomacromolecules like siRNA from degradation during the long circulation endowed by the PEG out layer. In addition, the acetal groups containing membranes provide a controllable drug release mechanism inside cancer cells. In order to enhance the cell uptake of the polymersomal drugs, tumor specific targeting units e.g. galactose or monoclonal antibodies (Avastin or Herceptin), are introduced onto the polymersome surfaces. Once the polymersomes (co)loaded with siRNA/anticancer drug are targeted to and internalized by tumor cells, the polymersomes will be triggered to release drugs quickly due to the endosomal pH triggered acetal cleavage and subsequent dissolution of the polymer into unimers which in turn result in the polymersome dissociation. The fast release might inhibit the multidrug resistance leading to high efficient cancer therapy. Therefore, the endosomal pH degradable chimaeric polymersomes are highly promising for high efficient targeted cancer therapy.

本项目将研制具不对称膜结构的pH敏感可降解智能聚合物囊泡用于亲水抗癌药、生物药和/或疏水抗癌药的高效包裹和快速细胞内释放，实现高效肿瘤靶向治疗。该囊泡由聚乙二醇-聚（2,4,6－三甲氧基苯甲缩醛－1,1,1－三羟甲基乙烷甲基丙烯酸甲酯）-聚电解质 (PEG-PTTMA-PI)共聚物自组装形成，设计PEG比PI长，PEG选择性位于囊泡外，保证其良好生物相容性和长循环时间；PI选择性位于囊泡内腔，其通过静电或氢键作用实现带相反电荷亲水药（如DOX?HCl、siRNA）的高效包裹；由PTTMA组成的囊泡疏水壁膜可包裹PTX等疏水抗癌药，且其pH敏感降解性将导致囊泡在细胞内快速解离，实现靶细胞内高效药物释放。此外，通过引入单抗或半乳糖等生物分子，可望实现囊泡的高效且特异性肿瘤细胞内吞。该智能囊泡载体可同时高效运载siRNA等生物药和PTX等疏水抗癌药，有望实现高效肿瘤协同治疗，克服耐药性。

聚合物囊泡是亲水抗癌药物如大分子生物药和水溶性小分子抗癌药的理想载体，是开发高效低毒的抗肿瘤纳米药物的理想选择。但是在实际应用中还存在装载效率低、循环不稳定易发生药物早释、进靶细胞量少、药物释放慢、浓度低而易导致耐药性，而致使药效差、毒副作用大的问题。本项目针对这些关键科学问题开展研究， 设计了多种表面偶联肿瘤特异性靶向分子的智能囊泡体系，尤其是具有不对称膜结构的囊泡（CPs）和还原敏感可逆交联的囊泡（RCPs）,创新地实现了亲水抗癌药（蛋白质、siRNA、小分子药物如DOX•HCl等）的高效装载和肿瘤靶向治疗。本项目产生了如下重要研究成果：(1)研制的内涵体酸敏感的CPs实现了DOX•HCl和蛋白质的高效装载和癌细胞内有效输送；(2)设计的细胞内还原敏感、肿瘤靶向的生物可降解囊泡能将蛋白质高效输送到靶细胞内;(3) 设计合成的基于PHPMA和硫辛酸的还原敏感可逆交联的CPs可实现亲水药甲氨喋呤二钠和颗粒酶Ｂ的高效稳定装载、肺癌靶向输送和高效体内肿瘤抑制;(4)创新地设计合成了新型环碳酸酯1，2-二硫戊环三亚甲基碳酸酯（DTC），制备了基于DTC、肿瘤特靶向的还原敏感可逆交联的聚合物囊泡，这一完全生物可降解、生物相容性优异的聚合物囊泡技术平台实现了DOX•HCl的高效包裹、双硫交联循环稳定、高特异性细胞摄取、细胞内还原条件下可逆解交联而应激释放药物，在人肺癌、人卵巢癌、人脑胶质瘤、人结肠癌、小鼠黑色素瘤等小鼠肿瘤模型的靶向治疗上表现出色，为临床推进和转化奠定了基础。(5)研发的基于DTC、以PEI为正电荷内膜的CPs具有还原敏感可逆交联的性质，可高效装载和靶向输送蛋白质、siRNA或和培美曲塞到肿瘤细胞内，实现高效肿瘤抑制; (6)创新地设计合成了含双碘新型环碳酸酯单体，制备了肿瘤靶向、生物可降解聚合物囊泡纳米CT造影剂，用于肿瘤的早期诊断和RES系统疾病。本项目研究成果包括：发表论文42篇；影响因子总和超过300。其中1篇论文获中国百篇最具影响国际学术论文，6篇论文为ESI高被引论文。申请中国和国际专利30项，授权11项，专利转让10项，并正在进行临床转化研究；博士学位论文1篇，硕士学位论文8篇；负责人3次应邀在国际学术会议上做邀请报告。