Utilising DNA Vectors to persistently modify cells without the risk of insertional mutagenesis or transcriptional silencing

Our research is focused on generating novel, next-generation DNA vectors for gene therapy. We have developed a vector system, which is uniquely suited for the genetic modification of cells – it provides persistent expression and episomal maintenance without the use of potentially toxic viral components or the risk of insertional mutagenesis.  Additionally, it provides unlimited capacity allowing the unrestricted development of exquisitely designed and endogenously controlled genetic vectors which can comprise entire genomic loci. We have demonstrated the utility of these vectors in vitro, ex vivo and in vivo. The use of eukaryotic chromosomal components which exploit the interdependence of transcription and replication allows the design of clinically relevant, episomally sustained replicating DNA vectors that can be used to confer persistent expression of biologically relevant or corrective genes.

Prototype gene expression plasmid vector

We were the first group to demonstrate the utility of the S/MAR vector system for in vivo application and demonstrated its ability to sustain long-term transgene expression in the livers of mice from a single administration.We also showed by removing the extraneous bacterial sequences from the vector and utilising minicircles we could improve its efficiency and reduce its immunotoxicity. Additionally, we demonstrated for the first time that by generating a version of our vector which contained an in vivo selection marker we could stimulate the episomal replication of S/MAR transgenic DNA in vivo. A great advantage of this vector system is that it can be readily adapted for use in other tissues with the use of specific or ubiquitous promoters.

Permanent genetic modification of replicating cells without integration

We have also recently shown the utility of our episomal vectors for the persistent genetic modification and phenotypic correction of dividing cells in culture and for ex vivo application. Stable, genetically modified novel cell-lines can be prepared simply using our vector system and can be readily utilised for cell marking studies, stem-cell differentiation and in vivo tumour modelling.

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