Development of a targeted non-viral gene delivery system for cancer gene therapy

The clinical application of gene therapy is hampered by the lack of a gene delivery system that can efficiently deliver therapeutic genes to the target cells without eliciting serious immune response and toxicity. In this research, an amino acid based targeted gene delivery system has been described which is able to overcome multiple intracellular barriers for efficient and targeted gene delivery in vitro and in vivo. The first chapter is a review over literature serving as background information. In this section, the advantages and disadvantages of both viral and non-viral gene delivery systems are highlighted with emphasis on the application of biological motifs in gene delivery system design. In the second chapter, the development an amino acid based HER-2 targeted non-viral vector, namely GHT, is described. This vector is composed of several biological motifs with diverse functions for efficient and targeted gene delivery. A series of in vitro biochemical and biological assays were performed to evaluate the functionality of the vector. The results revealed that the biological functions of different motifs in the vector structure were well preserved and the vector facilitated the selective and efficient delivery of plasmid DNA to SKOV-3 cells for expression. In the third chapter, the in vivo therapeutic efficacy of the HER-2 targeted vector was evaluated. A thymidine kinase suicide gene mutant was used as a model gene for this purpose. A cytotoxicity assay was performed to show that there was no vector-related cytotoxicity. Cell killing and clonogenic assays were conducted on SKOV-3 cells to examine the acute and chronic toxicity of GHT/pTK-SR39 system. The results showed that GHT/pTK-SR39 complexes in combination with GCV can kill up to 82% of SKOV-3 cells in vitro and 90% of the cells that survived lost their ability to proliferate and form colonies. The in vivo studies demonstrated that the GHT/pTK-SR39 complexes can significantly reduce tumor size when used in combination with GCV