Expression Of EphB4 And EphrinB2 In Midpalatal Suture Of Mice During Mechanical Force-expansion

Objective To detect the morphological changes in the midpalatal suture of mice during the mechanical force-expansion period and discuss the distribution and significance of osteoblast in the suture remodeling during the expansion.Methods Twenty five six week-old male C57BL/6 mice were subjected to palatal suture expansion by opening loops with an initial force of 0.49 N for the periods of 1, 3, 5, 7, 14 days. The sequence of histological changes in the midpalatal suture bone formation of animals was detected by hematoxylin eosin staining. Osteoblast were tested by alkaline phosphatase (ALP) staining.Results HE staining indicated that midpalatal suture was gradually expanded from 1d to 14d experimental group. And ALP staining shown: starting at day 1, cells expressing alkaline phosphatase was seen. New cartilage and bone formation was observed at the oral edges of the palatal bones at day 7.Conclusions These findings demonstrate that expansion forces across the midpalatal suture promote its expansion and the activation and proliferation of osteoblasts. Activity and the distribution of the osteoblasts is important to distraction osteogenesis in midpalatal suture of mice during mechanical force-expansion.0bjective To observe the expression EphB4/ephrinB2 in the maxillary palatal suture of mice during the mechanical expansion and to evaluate the significance of them on the suture remodeling during expansion.Methods Twenty five six-week-old male C57BL/6 mice were subjected to midpalatal suture expansion by opening loops with an initial force of 0.49 N for 1, 3, 7 and 14 days as experimental group. The tissue location and image analysis of EphB4 and ephrinB2 in the midpalatal suture was detected by immunohistochemical method. The expression of EphB4 and ephrinB2 changes in the midpalatal suture formation of animals was analised by western blot.Results Immunohistochemical staining showed that: EphB4 and ephrinB2 in the control group were positive. Compared with the control group, the experimental group, the positive area of EphB4 and ephrinB2 from experiment group increased gradually after 1d and 3d group reached the peak, and from 7d group EphB4 and ephrinB2 in the positive area began to decrease, but still stronger than the control group. Western blot analysis showed that: compared with the control group, 1d, 3d, 7d, 14d EphB4 and ephrinB2 the experimental group had increased levels of protein expression, in 3d experimental group the expression of EphB4 and ephrinB2 significantly higher and the other experimental group (P <0.05). Western blot results are consistent with the morphological analysis.Conclusions These findings demonstrated that expansion forces across the midpalatal suture could promote the expression of EphB4 and ephrinB2, and it might play an important role in the bone formation and bone remodeling process.