Effect Of Forces On Osteogenic Factor Expression In hPDL Cells

Objectives: OBJECTIVE: To investigate the effects of vibration and compressive force on the expression of osteogenic factors; transforming growth factor beta (TGF- β), runt-related transcription factor 2 (RUNX2) and osterix (Osx) in human periodontal ligament (hPDL) cells

Methods: METHODS: The primary cultured hPDL cells were randomly divided into 4 groups: control without mechanical stimulus, mechanical vibration, compressive force, and combination of vibration and compressive. The cells in vibration group were subjected to vibration at frequency 30 Hz, magnitude 0.3g, 20 min, every 24 hours. The cells in compressive force group were received static compressive force of 1.5 g/cm². At 24, 48 and 72 h after each treatment, the RUNX2, Osx and TGF- β mRNA expression were determined using quantitative real-time polymerase chain reaction (qPCR).

Results:
RESULTS: In the mechanical vibration group, TGF-β was increased at 24 hours, RUNX2 was increased at 48 hours and then declined, Osx was increased at every time points comparing to the control. In the compressive force group, TGF- β and Osx were decreased at 24 hours comparing to the control, while RUNX2 expression was unchanged at every time point. When cells were exposed to both mechanical vibration and compressive force, TGF- β, RUNX2, Osx were decreased in the same pattern of compressive force group, however, mRNA expression of RUNX2 and Osx in combination group were significantly decreased at 72 hours comparing to compressive force group.

Conclusions: CONCLUSIONS: Vibration upregulates TGF- β, RUNX2 and Osx expression in hPDL cells, these results suggest the possibility that vibration alone may enhance osteogenic differentiation. However, the combination of vibration and compression downregulate RUNX2 and Osx expression compared to compressed hPDL cells. These finding may suggest that vibration may not promote osteogenic differentiation at the compression side during orthodontic tooth movement.