Endosomal disruptors in non-viral gene delivery

Importance of the field: Non-viral gene delivery for the treatment of genetic and non-genetic diseases has been under investigation for several decades, but there has been very little application in patients because of poor gene expression and toxicity. Areas covered in this review: As gene delivery almost invariably involves endocytosis, many of its limitations are related to compartmentalisation of the transgene within the endosomes. Gene expression enhancers have become an essential part of manipulating endosomal release, as well as protecting transgene from intracellular degradation. However, disruption of the endosomes can also release proteases that have been shown to activate apoptotic pathways. What the reader will gain: An understanding of the role that endosomal release plays in the toxicity of gene delivery vehicles will help identify new approaches to minimise adverse effects while enhancing non-viral gene expression. Take home message: The future of non-viral gene therapy needs to identify new approaches that limit endosome-induced toxicity while enhancing expression so that a pharmacological response can be reliably observed in vivo.