Non-linear stress-strain measurements of ex vivo produced oral mucosal equivalent (EVPOME) compared to normal oral mucosal and skin tissue

Abstract

Stress-strain curves of oral mucosal tissues were measured using direct mechanical testing. Measurements were conducted on both natural oral mucosal tissues and engineered devices, specifically a clinically developed ex vivo produced oral mucosal equivalent (EVPOME). As seeded cells proliferate on EVPOME devices, they produce a keratinized protective upper layer which fills in surface irregularities. These transformations can further alter stress-strain parameters as cells in EVPOME differentiate, more similar to natural oral mucosal tissues in contrast to an unseeded scaffold. In addition to tissue devices grown under normal conditions (37 °C), EVPOMEs were also produced at 43 °C. These thermally stressed specimens model possible failure mechanisms. Results from a mechanical deformation system capable of accurate measurements on small (approximately 1.0-1.5 cm(2)) cylindrical tissue samples are presented. Deformations are produced by lowering a circular piston, with a radius smaller than the sample radius, onto the center of the sample. Resulting force is measured with a precision electronic balance. Cultured EVPOME was less stiff than AlloDerm®, but similar to native porcine buccal tissue. Porcine skin and porcine palate tissues were even less stiff. Thermally stressed EVPOME was less stiff than normally cultured EVPOME as expected because stressed keratin cells were damaged reducing the structural integrity of the tissue.