Effects of Low Amplitude, High Frequency Vibrations on Proliferation and Differentiation of SAOS-2 Human Osteogenic cell line.

The aim of the work is to understand the consequences of low amplitude, high frequency vibrations on proliferation and differentiation of SAOS-2 cells (sarcoma osteogenetic), an osteoblastic and tumorigenic cell line. We realized a bioreactor composed by an eccentric motor which produces a displacement of 11 mm at frequencies between 1 and 120 Hz on a plate connected to the motor. The cultures of SAOS-2 cells were fixed on the plate and the linear acceleration provoked by the motor to the cultures was measured. We used 30 Hz as stimulating frequency after a preliminary test on the effect of different frequencies on differentiation of cells. Afterwards SAOS-2 cells were stimulated with 30 Hz for different durations, every day for 4 days. The expression of some genes involved in the differentiation process was analyzed firstly with a rt-PCR and afterwards with a real time PCR on the most expressed genes. Moreover the proliferation of cells was evaluated. The results suggest a strong increase in the expression of the genes involved in tissue differentiation in the treated groups with respect to the controls. On the other hand, the proliferation seems to be slowed down, so probably the acceleration perceived by the mechanosensors of the cells changes the cellular cycle by blocking the duplication in order to early differentiate toward bone tissue.