The Effect Of Dexamethasone On The Cell Adhesion And Mineralization Of Cementoblasts In Vitro

Objective：Root resorption is one of the most common side effects in orthodontictreatment. It occurs when the balance of the resorption and regeneration is disturbed.Cementum, a layer of connective tissue covered on the surface of the root, is animportant structure established between the periodontal ligament and rootattached.The differentiation and maturation of the cementoclast progenitor would beactivated by inflammatory conditions and abnormal force stimulation, that cause ofcementum destruction, and even lead to irreversible root resorption. Cementoblastslocate in periodontal ligament, lining on the root surface. It can not only prevent thecementoclast from attaching, but also form new cementum-like tissue to repair theresorpted root surface. But the mechanism of cementoblasts repairing resorpted root isstill unclear, and therefore, relative researches seem quite essential. Dexamethasone,which is a kind of steroid hormone, play an important role in osteogenesis treatment.It can enhance the ability of the osteoblast mineralization. In the regard, this study isaimed to examine the effects of dexamethasone on murine cementoblasts OCCM-30 in vitro as to provide theoretical basis for cementum regeneration.Method：A murine immortalized cementoblast cell line (OCCM-30) was cultured inthe presence of dexamethasone at three concentrations:1×10-5mol/L,1×10-6mol/Land1×10-7mol/L. After72hours, total RNA was isolated, and mRNA levels forbone/cementum markers, including alkaline phosphotase (ALP), bone sialoprotein(BSP), osteocalcin (OCN), osteopontin (OPN), and runt-related transcriptionfactor-2(Runx2), cell adhesion molecules (CAMs) such as Cadherin-11andN-Cadherin, were investigated by real-time quantitative reversetranscription-polymerase chain reaction (Q-PCR). Alkaline phosphotase activity andthe proliferation of cementoblast were also detected. Mineral nodule formation wasassayed on day8using Alizarin red staining.Result：The proliferation of OCCM-30treated by dexamethasone at1×10-4mol/Lwas significantly declined than that of control. Mineralized tissue markers werestrongly regulated by dexamethasone, with an almost six-fold increase in BSPtranscripts and significant increases in ALP, OCN and Runx-2mRNA expressions.Dexamethasone tended to increase the mRNA expression of Cadherin-11andN-Cadherin. Dexamethasone treatment markedly stimulated alkaline phosphotaseactivity and cementoblast-mediated biomineralization in vitro compared to untreatedcells.Conclusion：Dexamethasone can promote the adhesion and mineralization of the cementoblasts.These results support the promising applications of dexamethasone in therapiesaimed at regenerating periodontal tissues lost as a consequence of disease.