ABSTRACT
BACKGROUND: Hydrogen sulfide signaling has been proved to promote distraction osteogenesis; however,the underlying mechanism remains unclear.OBJECTIVE: To evaluate the relationship between hydrogen sulfide and hypoxia-inducible factor-1α (HIF-1α)during the osteogenesis of rat bone marrow mesenchymal cells under tensile stress.METHODS: 2000 μ strain was loaded on the in vitro cultured rat bone marrow mesenchymal cells by a four-point bending apparatus, and hydrogen sulfide donor or HIF-1α inhibitor was adopted in the tensile unit. Subsequently, the levels of osteogenic markers were detected.RESULTS AND CONCLUSION: Exogenous hydrogen sulfide signaling could promote the osteogenesis of rat bone marrow mesenchymal cells under tensile stress. However, this promotion was obviously eliminated when the endogenous HIF-1α expression was inhibited.These results show that hydrogen sulfide signaling system promotes the osteogenesis of rat bone marrow mesenchymal cells under tensile stress probably through HIF-1α.
ABSTRACT
OBJECTIVE: To investigate the involvement of ephrinB2 in periodontal tissue remodeling in compression areas during orthodontic tooth movement and the effects of compressive force on EphB4 and ephrinB2 expression in osteoblasts and osteoclasts. METHODS: A rat model of experimental tooth movement was established to examine the histological changes and the localization of ephrinB2 in compressed periodontal tissues during experimental tooth movement. RAW264.7 cells and ST2 cells, used as precursor cells of osteoclasts and osteoblasts, respectively, were subjected to compressive force in vitro. The gene expression of EphB4 and ephrinB2, as well as bone-associated factors including Runx2, Sp7, NFATc1, and calcitonin receptor, were examined by quantitative real-time polymerase chain reaction (PCR). RESULTS: Histological examination of the compression areas of alveolar bone from experimental rats showed that osteoclastogenic activities were promoted while osteogenic activities were inhibited. Immunohistochemistry revealed that ephrinB2 was strongly expressed in osteoclasts in these areas. Quantitative real-time PCR showed that mRNA levels of NFATc1, calcitonin receptor, and ephrinB2 were increased significantly in compressed RAW264.7 cells, and the expression of ephrinB2, EphB4, Sp7, and Runx2 was decreased significantly in compressed ST2 cells. CONCLUSIONS: Our results indicate that compressive force can regulate EphB4 and ephrinB2 expression in osteoblasts and osteoclasts, which might contribute to alveolar bone resorption in compression areas during orthodontic tooth movement.