We have previously demonstrated that LIPUS inhibited expression of sclerostin and stimulated new bone formation in a mouse osteotomy model. To further address effect of LIPUS on endochondral ossification, expression of sclerostin was examined in vitro.
ATDC5 cells were plated at initial density of 6 × 104 cells per well in a 6-multiwell plate and cultured in the presence of 5% FBS plus ITS. Some culture plates (LIPUS group) were treated with daily exposure of LIPUS from the bottom for 20 minutes, and the others (control group) were not. The culture media and cells were harvested at 1, 3 or 5 weeks for measurement of sclerostin expression.
Sclerostin was identified in the culture media at 3 and 5 weeks, and the concentration in LIPUS group was significantly less than that in the control group. PCR analysis demonstrated that sclerostin gene expression was significantly decreased in the LIPUS group in comparison to the control group at 3 and 5 weeks. And gene expressions of Col2a1 and Col10a1 were significantly decreased in the LIPUS group at 5 weeks.
This study suggested that expression of sclerostin in the process of endochondral ossification was inhibited by LIPUS treatment.