Effects of mechanical stress on cells derived from human oral mucosa

Abstract

Abstract Objective When a denture is applied, the oral mucosa is exposed to mechanical stress (MS) including occlusal force via the denture. Clinically, inflammation is occasionally observed in the oral mucosa immediately below the denture despite a proper fit. In this study, we applied MS to cells derived from human oral mucosa and evaluated its effects. Materials and Methods Subconfluent human oral mucosal epithelial cells (HO-1-N-1) and human gingival fibroblasts (HGF) were used to seed 1´105 cells/dish and, after 24 hours, subjected to MS (1 and 3 MPa, 60 min) using a hydrostatic pressurizer. Morphological changes of the cells were examined by Giemsa stain, and changes in cell activity were measured by the WST assay. In addition, mRNA was collected from the cells, and I Inflammatory cytokines and growth factors genes were measured by real-time RT-PCR assay and ELISA. Results HO-1-N-1 showed no morphological change by Giemsa stain but exhibited a significant decrease in cell activity by WST assay. Next, in HO-1-N-1, the expression of Inflammatory cytokines, and ICAM mRNA was significantly increased after MS at 1 MPa but was attenuated at 3 MPa. In HGF, the expression of IL-6 mRNA was enhanced. In HO-1-N-1 and HGF, the IL-6 and IL-8 protein levels increased significantly after MS. Furthermore, in HGF, the EGF and FGF-2 protein levels increased significantly by stimulation at 3 MPa. Discussion MS applied to the oral mucosa immediately below the denture caused a decrease in the activity of oral mucosal epithelial cells and induced enhancement of inflammatory cytokine production. Also, excessive MS was suggested to promote the cure of oral mucosa wounds by promoting the production of growth factors in the oral mucosa.