Zhao Jian, Wang Chunxiao, Zhao Peng, Wen Xuejun, Lin Chao
Key Laboratory of Rubber-Plastics, Ministry of Education and Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science & Technology, Qingdao, 266042, P. R. China.
J Mater Chem B. 2015 Feb 28;3(8):1529-1536. doi: 10.1039/c4tb01927j. Epub 2015 Jan 16.
The purpose of this work is to design a well-defined cationic dextran for intravenous gene delivery into tumor and examine the effect of the dextran on transfection efficacy in vivo. To this end, disulfide-linked dextran-linear polyethylenimine (Dex-SS-LPEI) conjugates were designed as non-viral vectors for intravenous gene delivery into tumor-bearing Balb/c nude mice. By coupling different molecular weights (2 kDa or 5 kDa) of LPEI disulfide pyridine to thiolated dextran (5 kDa or 10 kDa), Dex-SS-LPEI conjugates were prepared which have dextran as the main chain and disulfide-linked LPEI as the side chain. Dex-SS-LPEI conjugates can condense gene into nanosized polyplexes with moderate surface charge. Besides, the polyplexes of the conjugates have an improved colloidal stability under physiological conditions as compared to that of 22 kDa LPEI lacking dextran and can liberate gene by disulfide cleavage in an intracellular reducing environment. In vitro transfection experiments manifest that Dex-SS-LPEI conjugates mediate efficient gene transfection in different cells. The most efficient transfection in vitro was found for the conjugate with 5 kDa dextran and 5 kDa LPEI. Besides, Dex-SS-LPEI conjugates are practical for systemic gene delivery into tumor-bearing Balb/c nude mice by intravenous injection, affording comparable or higher transgene expression in HepG2 or SKOV-3 tumor than that yielded by 22 kDa LPEI as a positive control. Further, the polyplexes of the conjugate with 10 kDa dextran and 5 kDa LPEI can induce comparable transgene expression in the tumor but lower expression in the lung when compared to those of 22 kDa LPEI. The results of this study indicate that dextran plays a critical role in regulating in vivo gene delivery properties of Dex-SS-LPEI conjugates and transfection efficacy in tumor-xenografted nude mice. Dex-SS-LPEI conjugates have low cytotoxicity in vitro and cause no death of the mice, showing great potential as safe and highly efficient gene delivery vectors towards cancer gene therapy.
本研究旨在设计一种结构明确的阳离子葡聚糖用于静脉注射基因传递至肿瘤组织，并考察该葡聚糖对体内转染效率的影响。为此，设计了二硫键连接的葡聚糖-线性聚乙烯亚胺（Dex-SS-LPEI）共轭物作为非病毒载体，用于将基因静脉注射传递至荷瘤Balb/c裸鼠体内。通过将不同分子量（2 kDa或5 kDa）的二硫键吡啶化聚乙烯亚胺与巯基化葡聚糖（5 kDa或10 kDa）偶联，制备了以葡聚糖为主链、二硫键连接的LPEI为侧链的Dex-SS-LPEI共轭物。Dex-SS-LPEI共轭物能够将基因浓缩成具有适度表面电荷的纳米级多聚体。此外，与不含葡聚糖的22 kDa LPEI相比，该共轭物的多聚体在生理条件下具有更好的胶体稳定性，并且能够在细胞内还原环境中通过二硫键断裂释放基因。体外转染实验表明，Dex-SS-LPEI共轭物在不同细胞中介导高效的基因转染。体外转染效率最高的是含有5 kDa葡聚糖和5 kDa LPEI的共轭物。此外，Dex-SS-LPEI共轭物通过静脉注射将基因全身传递至荷瘤Balb/c裸鼠体内是可行的，在HepG2或SKOV-3肿瘤中产生的转基因表达与作为阳性对照的22 kDa LPEI相当或更高。此外，含有10 kDa葡聚糖和5 kDa LPEI的共轭物的多聚体在肿瘤中能够诱导相当的转基因表达，但与22 kDa LPEI相比，在肺中的表达较低。本研究结果表明，葡聚糖在调节Dex-SS-LPEI共轭物的体内基因传递特性以及在肿瘤异种移植裸鼠中的转染效率方面起着关键作用。Dex-SS-LPEI共轭物在体外具有低细胞毒性，不会导致小鼠死亡，作为安全高效的基因传递载体用于癌症基因治疗具有巨大潜力。
