Low magnitude high frequency vibration promotes chondrogenic differentiation of bone marrow stem cells with involvement of β-catenin signaling pathway

Mesenchymal stem cells (MSCs) are well known to have the capability to form bone and cartilage, and chondrogenesis derived from MSCs is reported to be affected by mechanical stimuli. This research aimed to study the effects of low magnitude high frequency (LMHF) vibration on the chondrogenic differentiation of bone marrow-derived MSCs (BMSCs) which were cultured with chondrogenic medium, and to investigate the role of β-catenin cascade in this process. Rat bone marrow-derived MSCs (BMSCs) were isolated and randomized into vibration and static cultures. The effect of vibration on BMSCs proliferation, differentiation and chondrogenic potential was assessed at the protein level. LMHFV did not affect the proliferation of BMSCs. However, this was accompanied by increased markers of chondrogenesis. The protein expression of chondrocyte-specific markers of Aggrecan, Sox9, and BMP7 were upregulated and Collagen X was decreased by LMHF vibration introduced at the chondrogenic differentiation in vitro. Specifically, thicker blue-stained particles were observed in Alcian Blue staining and the level of glycosaminoglycan were significantly increased respectively in the vibration culture group by 56.5 % and 93.6 % on the 7th and 14th day. The expression and nuclear translocation of β-catenin were activated in a significant manner. And inhibition of GSK-3β activity with Licl rearranged and intensified the cytoskeleton affected by vibration stimulation. Our data demonstrated that LMHF mechanical vibration promotes BMSCs chondrogenic differentiation and implies β-catenin signal acts as an essential mediator in the mechano-biochemical transduction and subsequent transcriptional regulation in the process of chondrogenesis.