In vitro and ex vivo models of the oral mucosa as platforms for the validation of novel drug delivery systems

The benefit of complex 3D models to facilitate the robust testing of new drugs and drug delivery systems during the developmental stages of pharmaceutical manufacturing has recently become distinguished within the field. Recognition of this need by the pharmaceutical industry has provided a motivation for research into the development of reliable complex models for use in drug delivery, biomaterials, and tissue engineering. Both 3D in vitro and ex vivo models can enhance drug-testing and discovery prospects over the more traditionally used 2D, monolayer culture systems and animal models. Despite the widespread acceptance that 3D tissue modelling is advantageous in this field, there remains a lack of standardisation in the models throughout literature. This article provides an extensive review of current literature on in vitro, and ex vivo models of the oral mucosa for drug delivery applications; the advantages, limitations, and recommendations for future development of improved models for this application.