Effect of Low-Intensity Pulsed Ultrasound (LIPUS) on Endochondral Ossification via the Wnt Signaling Pathway

OBJECTIVE: We have previously demonstrated that LIPUS stimulates endochondral ossification with decreased expression of sclerostin. The Wnt signaling pathway was examined in vitro to further address the effect of LIPUS on endochondral ossification. MATERIALS AND METHODS: ATDC5 cells were plated at an initial density of 6 × 10 cells/well in a 6-multiwell plate and cultured in the presence of 5% FBS plus ITS. The bottom of the culture plate was treated every day with LIPUS for 20 minutes. The level of calcification and the expression of Wnt signaling were investigated. RESULTS: The area of calcified nodules in the LIPUS-treated group was significantly greater than in the control group. The expression of Wnt was significantly elevated by LIPUS exposure. Markers associated with endochondral ossification were increased in the LIPUS-treated group. When sclerostin was added to the culture media, calcified nodule formation and the expression of Wnt were inhibited in both the LIPUS-treated group and the control group. DISCUSSION: This study suggests that endochondral ossification was stimulated by LIPUS via the Wnt signaling pathway.