Non-viral polyplexes: Scaffold mediated delivery for gene therapy

Non-viral gene delivery is emerging as a realistic alternative to the use of viral vectors with the potential to have a significant impact on clinical therapies. The documented dangers of using the efficient recombinant viruses as carriers have led many to explore the possible advantages of using polymer-based non-viral vectors. To date there is no gene delivery vehicle that contains all the desirable characteristics but they do exist individually in a variety of non-viral carriers, e.g. degradable, low toxicity, cell specific, relatively efficient and capable of delivering multiple genes. Polymers may not be as effective as the viral vehicles; however, the continued focus and growth of knowledge in this field has already resulted in improved delivery. Over the past 10 years, significant progress has been made through the design of specific polymers for this application. Another interesting development in this field is the influx of research on combination approaches to non-viral gene delivery. Scaffolds made of both natural and synthetic materials are being utilized to aid in sustained delivery of the polymer vectors. While the non-viral gene therapy field is currently receiving a large degree of dedicated research there is now the realistic potential of a clinically relevant output. This review presents a summary of combinatorial delivery systems of non-viral polyplexes delivered via tissue engineered scaffolds. For polyplexes to move into the clinical arena, it is important that we uncover and understand the technical hurdles that need to be overcome so that the efficacy of this promising technology can be established.