Department of Chemistry , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States.
Acc Chem Res. 2019 May 21;52(5):1347-1358. doi: 10.1021/acs.accounts.8b00665. Epub 2019 Apr 17.
The field of gene therapy, which aims to treat patients by modulating gene expression, has come to fruition and has landed several landmark FDA approvals. Most gene therapies currently rely on viral vectors to deliver nucleic acid cargo into cells, but there is significant interest in moving toward chemical-based methods, such as polymer-based vectors, due to their low cost, immunocompatibility, and tunability. The full potential of polymer-based delivery systems has yet to be realized, however, because most polymeric transfection reagents are either too inefficient or too toxic for use in the clinic. In this Account, we describe developments in carbohydrate-based cationic polymers, termed glycopolymers, for enhanced nonviral gene delivery. As ubiquitous components of biological systems, carbohydrates are a rich class of compounds that can be harnessed to improve the biocompatibility of non-native polymers, such as linear polyamines used for promoting transfection. Reineke et al. developed a new class of carbohydrate-based polymers called poly(glycoamidoamine)s (PGAAs) by step-growth polymerization of linear monosaccharides with linear ethyleneamines. These glycopolymers were shown to be both efficient and biocompatible transfection reagents. Systematic modifications of the structural components of the PGAA system revealed structure-activity relationships important to its function, including its ability to degrade in situ. Expanding upon the development of step-growth glycopolymers, monosaccharides, such as glucose, were functionalized as vinyl-based monomers for the formation of diblock copolymers via radical addition-fragmentation chain-transfer (RAFT) polymerization. Upon complexation with plasmid DNA, the glucose-containing block creates a hydrophilic shell that promotes colloidal stability as effectively as PEG functionalization. An N-acetyl-d-galactosamine variant of this diblock polymer yields colloidally stable particles that show increased receptor-mediated uptake by liver hepatocytes in vitro and promotes liver targeting in mice. Finally, the disaccharide trehalose was incorporated into polycationic structures using both step-growth and RAFT techniques. It was shown that these trehalose-based copolymers imparted increased colloidal stability and yielded plasmid and siRNA polyplexes that resist aggregation upon lyophilization and reconstitution in water. The aforementioned series of glycopolymers use carbohydrates to promote effective and safe delivery of nucleic acid cargo into a variety of human cells types by promoting vehicle degradation, tissue-targeting, colloidal stabilization, and stability toward lyophilization to extend shelf life. Work is currently underway to translate the use of glycopolymers for safe and efficient delivery of nucleic acid cargo for gene therapy and gene editing applications.
基因治疗领域旨在通过调节基因表达来治疗患者，目前已经取得了成果，并获得了美国食品和药物管理局（FDA）的多项批准。目前大多数基因疗法都依赖于病毒载体将核酸货物递送到细胞中，但由于其低成本、免疫相容性和可调节性，人们对转向基于化学的方法（如基于聚合物的载体）产生了浓厚的兴趣。然而，基于聚合物的递药系统的全部潜力尚未得到实现，因为大多数聚合物转染试剂要么效率太低，要么毒性太大，无法在临床上使用。在本报告中，我们描述了用于增强非病毒基因传递的基于碳水化合物的阳离子聚合物，即糖聚合物的发展。碳水化合物作为生物系统的普遍成分，是一类丰富的化合物，可以用来提高非天然聚合物的生物相容性，例如用于促进转染的线性多胺。Reineke 等人通过线性单糖与线性亚乙基亚胺的逐步聚合，开发了一类新型的基于碳水化合物的聚合物，称为聚（糖酰胺）（PGAA）。这些糖聚合物被证明是高效且具有生物相容性的转染试剂。对 PGAA 系统结构成分的系统修饰揭示了其功能的结构-活性关系，包括其原位降解的能力。在逐步聚合糖聚合物的基础上，葡萄糖等单糖被功能化为乙烯基单体，通过自由基加成-断裂链转移（RAFT）聚合形成嵌段共聚物。与质粒 DNA 络合后，含葡萄糖的嵌段形成亲水性壳，可有效促进胶体稳定性，与聚乙二醇（PEG）功能化的效果相当。该嵌段共聚物的 N-乙酰-D-半乳糖胺变体在体外表现出增加的受体介导的肝实质细胞摄取，并在小鼠中促进肝脏靶向。最后，使用逐步聚合和 RAFT 技术将二糖海藻糖纳入阳离子结构中。结果表明，这些基于海藻糖的共聚物赋予了更高的胶体稳定性，并生成了在冻干和水复溶时抵抗聚集的质粒和 siRNA 聚集体。上述一系列糖聚合物通过促进载体降解、组织靶向、胶体稳定和抵抗冻干再水合时的聚集来延长保质期，从而利用碳水化合物促进核酸货物有效且安全地递送到多种人类细胞类型中。目前正在努力将糖聚合物用于安全有效地递送核酸货物，用于基因治疗和基因编辑应用。
