Biosynthetic response of cultured articular chondrocytes to mechanical vibration.

The objective of this study was to determine the effects of mechanical vibration loading on DNA and proteoglycan syntheses in cultured rabbit articular chondrocytes. Chondrocyte culture plates were placed in a vibratory apparatus and subjected to a mechanical vibratory load at various frequencies and periods in culture. Mechanical vibration was applied at a sinusoidal waveform of 1.4 g acceleration with frequencies of 200, 300, 400, 800, and 1600 Hz. 3H-Thymidine and H2(35)SO4 incorporation were used to detect radiolabeled DNA and proteoglycan syntheses, respectively. A frequency of 300 Hz showed a time-dependent augmentation of DNA synthesis and gave a maximal increase at day 3 with periodic vibration (8 h per day) and at 72 h or longer with continuous vibration. It also promoted proteoglycan synthesis in long-term culture (from 3 to 15 days) by periodic vibration. However. frequencies above 400 Hz suppressed biosynthesis. These results suggest that mechanical vibration at certain frequencies may modulate biosynthetic response of articular chondrocytes.