The development of a novel and efficient HAC vector delivery system to human cells

Human Artificial Chromosomes (HACs) have been confirmed as viable gene expression vectors and a potential tool for gene therapy. However, standard lipid-based delivery methods pose a developmental barrier. The work presented in this thesis includes the development of a novel and efficient HAC vector system for gene delivery into human cells using Herpes Simplex Virus-1 (HSV-1) amplicon technology. The development of HSV-1 amplicons for HAC delivery is a major step forward in the HAC field. In this study, utilising the technology allowed the generation of HACs at a high efficiency in a range of human cell types, which is a significant step in the development for HAC gene expression systems. Further work also showed a significant difference in HAC stability between cell lines. Real-time PCR analysis determined that Aurora B was over expressed in cell lines in which the HACs were unstable. This correlated with high levels of chromosomal instability and was confirmed by western blot analysis. Since Aurora B is a kinase involved in at least two cell cycle checkpoints, cellular phosphorylation levels were perturbed to mimic that observed in the unstable cells, using okadaic acid, which is both a protein phosphatase inhibitor and activates Aurora B. Treatment of cells showed an increase in both HAC and overall chromosomal instability and an increase in histone H3 Serine 10 and Serine 28 phosphorylation. The project also focussed on the development of a gene expression system using HSV-1 amplicons. Two different strategies were explored. Firstly, one approach involved engineering the HPRT genomic locus into an HSV-HAC vector, by Red mediated recombination for complementing the HPRT deficiency in HPRT- HT1080 cells. As an alternative approach, co-infection of two different HSV-1 HAC amplicons for generating a single HAC gene vector was investigated. Initial experiments utilising the latter approach were the most successful and show promise for generating HAC containing genes via this strategy