A new in vitro mechanical pressure system simulating orthodontic force

Orthodontic pressure force is mediated by the fibroblasts of the PDL. In previous studies we have shown that in vivo pressure force induces the transcription and activity of MMP-1. However, the mechanism of cell sensing pressure force is unknown.Objective: to established an in-vitro model suitable for prolonged application of pressure on cultured cells.Material and methods: Cultured human periodontal fibroblasts cells were injected into a culture chamber compose of two optically clear gas-permeable growth polystyrene membranes pre-coated with collagen type-I. After cells attachment, direct load was applied on the chamber which induces hydrostatic pressure.Results: The ratio between the applied pressure and the actual pressure measured by a barometer was found to be 0.8. Cell vitality was tested by Trypan blue and was 98% following 24 hours of application of continuous pressure level of 40gr/cm2. Protein chip (Hypomatrix, USA) screening test revealed an increase in phosphorylation of Focal Adhesion Kinase beta Catenin and RelB. Conclusions: We present a new tool to investigate the effect of pressure force on cultured cells. This model allows the examination of prolonged continued or intermittent force. The preliminary results imply that the initial cellular response is associated with signal transduction events.