Response to Light Compressive Force in Human Cementoblasts in vitro

Objectives: Cementum receives various mechanical stimuli such as occlusal forces, orthodontic force and trauma in clinical settings. However, response to compressive force has not been known in human cementoblast. In the present study, we investigated response such as cell growth, morphology, and the expression of differentiation markers to light compressive force in a human cementoblast cell line.
Methods: Immortalized human cemetoblast cells (HCEM) were spread in 35-mm dish (1 x 10⁴) and loaded for 12 h by mounting coverslips (0.25 gf/cm²). The coverslips were then removed and the cells were cultured for up to 21 days. Cell growth, morphological changes, and the mRNA expression of RUNX2, ALP, WNT5A and SPON1 were investigated. Cells without glass loading were used as controls.
Results: No significant differences were observed in cell numbers between the compressed group and control group until day 7. Morphology of the compressed cells was slightly flattened on day 0; however, no indications of cell death were detected in compressed groups. Expression of differentiation markers including RUNX2, ALP and WNT5A was significantly lower in the compressed group (0.7, 0.75 and 0.75-fold respectively; n=7, P<0.05) than in the control group on day 7. The expression levels of SPON1, a differentiation marker of cementoblasts, were higher on days 7 and 14 than on day 0, but were statistically lower in the compressed group than in the control group (n=7, P<0.01).
Conclusions: These results suggest that light compressive force does not affect cell growth and morphology, but restrains higher expression of cementogenic differentiation markers in human cementoblasts in vitro.

Supported, in part, by the Japanese Ministry of Education, Culture, Sports, Science and Technology, Grant-in-Aid No. 25462878.