Tailored Polymers for Delivery of Gene Medicines

用于基因药物递送的定制聚合物

• 批准号: RGPIN-2014-04460
• 负责人: Uludag, Hasan
• 金额: $ 2.11万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=667371
• 关键词: Tailored; Polymers; Delivery; Gene; Medicines

Molecular therapy offers the best promise of a cure for a wide range of genetic disorders. The ability to permanently `fix' defective genes is desirable over current drug therapy, which typically do little to eradicate the underlying cause of the disease. Successful molecular therapy involves a precise knowledge of a gene defect in a disease, followed by delivery of nucleic acids to modulate gene expression. It is possible to enhance gene expression by delivering plasmid DNAs (pDNA) or silence gene expression by delivering short interfering RNA (siRNA). But therapeutic success is absolutely dependent on the use of gene carriers since nucleic acids cannot be internalized by cells. Cationic polymers are safe delivery vehicles for this purpose but they suffer from low transfection efficiencies and high toxicities. This Discovery Project aims to create `engineered' polymers that can self-assemble with nucleic acids to create nanoparticles ideal for cellular delivery. * *We have been engineering a class of amphiphilic polymers constructed from hydrophobic lipids and cationic polymers. Our work has led us to low molecular weight (0.6 - 2.0 kDa) polyethylenimines (PEI) as the optimal starting material. Hydrophobic moieties were found to create bridges among self-assembled nanoparticles, stabilizing the structure via lipid-lipid associations and enhancing delivery of the cargo into cells by as much as 10-fold. A specific issue not addressed in the previous funding period was controlled delivery and release of the cargo, which is needed for optimal functional outcomes. The proposed project is intended to address this issue. Our overall hypothesis is: amphiphilic polymers can be engineered from cationic polymers and lipids for controlled delivery and release of nucleic acids in cells, ultimately leading to improved functional outcomes mediated by nucleic acids. Structure-function relationships will be pursued to better understand limiting barriers for delivery of nucleic acids and approaches to overcome these barriers. Specific aims of this project are:*Aim-1. To design a library of small molecular weight (<2 kDa) amphiphilic polymers with improved lipid substituents for endosomal escape. Our previous work explored a limited range of lipids and established preliminary information on functional features for endosomal escape. This effort will be expanded by exploring other lipid substituents with promising functional features. The relevant physicochemical properties of the polymer library will be characterized as well as cellular delivery of nucleic acids. *Aim-2. To conjugate effective lipids to polymers via labile linkages. Using short polymeric backbones, the chosen lipids will be anchored onto polymer backbones via cleavable linkages. The stability of the polymers will be characterized as well as the intracellular trafficking of resultant nanoparticles.*Aim-3. To determine functional performance of polymers for nucleic acid delivery. We anticipate the properties of self-assembled complexes formed between polymeric carriers and nucleic acids to dictate the functional outcomes. This aim will probe the functional outcomes in relevant cellular systems in vitro.* *The outcome of the proposed project will have significant impact on development of molecular therapies for human diseases. A foundation for polymer-guided delivery of genetic agents will be established by exploring the effectiveness of safer alternatives (i.e., polymers) to current delivery vehicles (i.e., viruses). While exploring molecular assembly into nanoparticles, functional materials for effective and safe application of molecular therapy will be developed as a result of successful completion of this project.

分子疗法为治疗多种遗传疾病提供了最好的希望。永久“修复”缺陷基因的能力比目前的药物治疗更可取，而目前的药物治疗对根除疾病的根本原因几乎没有作用。成功的分子治疗包括对疾病中基因缺陷的精确了解，然后传递核酸来调节基因表达。可以通过传递质粒dna （pDNA）来增强基因表达，或者通过传递短干扰RNA （siRNA）来沉默基因表达。但是治疗的成功完全依赖于基因载体的使用，因为核酸不能被细胞内化。阳离子聚合物是安全的载体，但其转染效率低，毒性高。这个发现项目旨在创造“工程”聚合物，这种聚合物可以与核酸自组装，从而制造出理想的细胞递送纳米颗粒。* *我们一直在设计一类由疏水脂质和阳离子聚合物构成的两亲性聚合物。我们的工作使我们找到了低分子量（0.6 - 2.0 kDa）的聚乙烯亚胺（PEI）作为最佳的起始材料。疏水部分被发现在自组装的纳米颗粒之间建立桥梁，通过脂质-脂质结合来稳定结构，并将货物运送到细胞中的速度提高了10倍。在上一个资助期内没有解决的一个具体问题是控制货物的交付和释放，这是实现最佳功能结果所必需的。拟议的项目旨在解决这一问题。我们的总体假设是：两亲性聚合物可以由阳离子聚合物和脂质工程化，以控制核酸在细胞中的传递和释放，最终导致由核酸介导的功能结果的改善。我们将继续研究结构-功能关系，以更好地了解核酸传递的限制障碍和克服这些障碍的方法。该项目的具体目标是：*目标-1。设计一个小分子量（<2 kDa）两亲性聚合物库，改进脂质取代基，用于内体逃逸。我们之前的工作探索了有限范围的脂质，并建立了关于内体逃逸功能特征的初步信息。这项工作将通过探索其他具有有前途的功能特征的脂质取代基来扩大。相关的物理化学性质的聚合物库将被表征，以及细胞传递的核酸。* Aim-2。通过不稳定键将有效脂质与聚合物共轭。使用短聚合物骨架，所选的脂质将通过可切割连接锚定在聚合物骨架上。聚合物的稳定性将被表征，以及由此产生的纳米颗粒的细胞内运输。测定聚合物的核酸传递功能性能。我们预计在聚合载体和核酸之间形成的自组装复合物的性质决定了功能结果。这一目的将探讨相关细胞系统的体外功能结果。* *拟议项目的结果将对人类疾病分子疗法的发展产生重大影响。通过探索更安全的替代品（即聚合物）取代目前的运载工具（即病毒）的有效性，将为聚合物引导的遗传制剂递送奠定基础。在探索分子组装成纳米粒子的同时，本项目的成功完成将开发出有效、安全应用于分子治疗的功能材料。