High-magnitude mechanical strain inhibits the differentiation of bone-forming XXXX calvarial progenitor cells.

@entity6037 @entity21408 @entity460 @entity2095 @entity35
PURPOSE: Orthodontic tooth movement occurs during the bone remodeling induced by therapeutic mechanical strain. It is important to investigate the relation between the strength of mechanical stress and bone formation activity. The aim of this study was to determine the effect of high-magnitude mechanical strain on bone formation in detail. MATERIALS AND METHODS: Osteoblast-like cells isolated from fetal @entity35 calvariae were loaded with 18% cyclic tension force (TF) for 48   h. To phenotypically investigate the effect of TF, we measured the number and the size of bone nodules stained by von Kossa technique on day 21 after cell seeding and determined the @entity460 content of bone nodules on day 14. Furthermore, we examined the gene expression of @entity2095 , @entity6037 and @entity21408 , which are important factors for bone nodule formation, on days 1, 4 and 7 after TF loading. RESULTS: The maximum bone nodule size in the control group was 1620 and 719    m in the TF group. Furthermore, the mean number of bone nodules sized over 360    m in the TF group was significantly decreased compared to the control group. The @entity460 content was also significantly decreased to 42% by TF loading. The mRNA expression of @entity2095 , @entity6037 and @entity21408 was decreased 1 and 4 days after TF loading. CONCLUSION: The differentiation of bone forming progenitor cells into bone nodule forming cells was inhibited by TF due to the decreased expression of bone formation related factors such as @entity2095 , @entity6037 and @entity21408 .
