Veterinary pharmaceutics in Australia

Abstract

Although most research on gene therapy has focused on the development of viral-mediated approaches to deliver therapeutic genes to cells both ex vivo and in vivo, non-viral gene medicines have emerged as a potentially safe and effective gene therapy method for the treatment of a wide variety of acquired and genetic diseases. Gene medicines consist of both a gene expression system that contains a therapeutic gene and a synthetic gene delivery system. Gene expression systems can be constructed to control the location, amount and duration of in vivo production of a therapeutic protein. A gene delivery system controls the distribution and access of a gene expression system to a target tissue, its recognition by cell-surface receptors and its intracellular trafficking. As each biological target will require a unique gene delivery and gene expression system, many of the principles and methods established in developing advanced drug delivery systems can be applied to the design and preparation of synthetic gene delivery systems. This paper describes different approaches taken to protect and to enhance the delivery of gene expression systems to target cells. Self-assemblies of condensing carriers, such as cationic liposomes, synthetic polymers and peptides, with a gene expression system are described. The characterization of the resulting particulate gene medicines is reported, as is the influence of their physicochemical properties on the efficiency of gene delivery. This contribution also describes approaches to effect the intracellular trafficking of a gene expression system to the nucleus of a target cell, in particular by using synthetic amphipathic peptides to control the endosomal release of plasmid DNA.