Improving non-viral gene delivery with histone-targeted polyplexes: uptake, trafficking, and nuclear deposition

Abstract

Delivery of nucleic acids for therapeutic applications is an exciting field, promising innovative approaches for regulating protein expression towards the treatment of diseases including multiple varieties of cancer. The focus of this field is to develop efficacious delivery vehicles which can shuttle therapeutic nucleic acids into cells in a nontoxic manner, leading to treatment of diseases on a molecular level. However, the efficiency of non-viral delivery vehicles has been limited by an incomplete understanding of their cellular uptake, subcellular trafficking, and intracellular delivery to the nucleus. This dissertation focuses on experiments designed to elucidate the biological properties of the histone H3 tail peptide utilized for DNA delivery vehicles, and how they enhance gene delivery. We have found that these H3 tail peptides, in combination with the cationic polymer poly(ethylenimine) (PEI), can effectively bind and protect plasmid DNA (pDNA), for efficient delivery to the nucleus. The studies described in this dissertation focus on elucidating the endocytic pathway and nuclear delivery mechanisms of H3-targeted polyplexes in mammalian cell lines. These studies demonstrate that (1) the caveolar endocytic pathway plays a vital role in the fate of polyplexes, (2) H3-targeted polyplexes interact with histone effectors to effectively enter the nucleus during mitosis, and (3) H3-targeted polyplexes selectively target cancer cells that overexpress caveolin. In total, this dissertation provides new evidence for the potential role for histone-based materials as effective gene transfer vehicles, and supports the importance of subcellular trafficking for non-viral gene delivery. Ultimately, gene therapies will rely on the development of methods to control gene targeting and trafficking along the delivery pathway, requiring properties that enable them to appropriately navigate the intracellular space. This dissertation contributes to the growing body of literature to improve our fundamental understanding of the processing of non-viral carriers.