Finite element model of the non-keratinized buccal tissue under the impact of negative pressure

The buccal mucosa is a highly interesting site for non-invasive drug delivery due to its relatively permeable epithelium and good accessibility. Recently, device-based systems have enabled the delivery of macromolecular drugs by leveraging mechanical stretching forces on the tissue to assist drug diffusion. Despite the successful exploitation of the buccal route with such systems, the biomechanics of buccal tissue are still poorly characterized and understood due to a lack of adequate characterization methods. Therefore, we propose a combination of physiological tissue modeling with simple suction experiments as a tool for characterizing and understanding the buccal tissue under the impact of negative pressure. Here, we present an initial step towards a multiphasic and poroelastic model specifically designed for the non-keratinized buccal tissue under the impact of negative pressure. A validated finite element model (FEM) for human skin was adapted to represent the histological structure of porcine buccal tissue. We performed suction experiments using the NIMBLE device, specifically developed for measuring skin stiffness, to characterize its mechanical behavior and train the FEM model. The resulting simulation tracks essential physiological parameters and allows the prediction of measurable changes in the tissue, such as the thinning of the epithelium and single-cell stretching. The FEM simulation was validated through histochemically stained tissue sections at the NIMBLE application site. A good correlation was demonstrated between predicted and experimentally observed changes. This work serves as a first step towards a computational representation of buccal tissue under the impact of negative pressure.