Gene delivery for periodontal tissue engineering: current knowledge - future possibilities

The cellular and molecular events of periodontal healing are coordinated and regulated by an elaborate system of signaling molecules, pointing to a primary strategy for functional periodontal compartment regeneration to replicate components of the natural cellular microenvironment by providing an artificial extracellular matrix (ECM) and by delivering growth factors. However, even with optimal carriers, the localized delivery of growth factors often requires a large amount of protein to stimulate significant effects in vivo, which increases the risk and unwanted side effects. A simple and relatively new approach to bypassing this dilemma involves converting cells into protein producing factories. This is done by a so-called gene delivery method, where therapeutic agents to be delivered are DNA plasmids that include the gene encoding desired growth factors instead of recombinant proteins. As localized depots of genes, novel gene delivery systems have the potential to release their cargo in a sustained and controlled manner and finally provide time- and space- dependent levels of encoded proteins during all stages of tissue regrowth, offering great versatility in their application and prompting new tissue engineering strategy in periodontal regenerative medicine. However, gene therapy in Periodontology is clearly in its infancy. Significant efforts still need to be made in developing safe and effective delivery platforms and clarifying how gene delivery, in combination with tissue engineering, may mimic the critical aspects of natural biological processes occurring in periodontal development and repair. The aim of this review is to trace an outline of the state-of-the-art in the application of gene delivery and tissue engineering strategies for periodontal healing and regeneration.