A biofidelic in vitro model to determine the tribological behaviour of mucous layers and their influence on tissue damage

Mucous boundary layers on epithelial tissues facilitate mechanical interactions during sliding contact in the mouth, while the loss of mucous lubrication may lead to lubrication failure, tissue exposure and mechanical trauma from direct contact between sliding tissues. This study introduces a biofidelic model created by adhering human oral squamous epithelial cells onto polydimethylsiloxane (PDMS) in the presence of a lubricating layer provided by either porcine gastric mucins (PGM) or bovine submaxillary mucins (BSM). The integration of mucous lubrication and a cell monolayer in tribological studies offers a novel approach for simultaneously evaluating friction and cell monolayer damage induced by alterations in the lubricating layer. Dynamic light scattering (DLS), tribometry, and live-dead cell assays revealed that BSM outperformed PGM in reducing friction and minimizing cell damage. BSM showed the lowest coefficient of friction (COF) compared to the absence of mucins which resulted in a 300% increase in COF (p = 0.01) and a 150% increase compared to PGM (p = 0.04). PGM mucous layers increased cell damage from 17% to 38%, while BSM mucous layers reduced cell damage to about 7%, demonstrating a protective effect, superior to both the absence of mucins and the presence of PGM.