Biosynthetic response of cultured articular chondrocytes to mechanical vibration

The objective of this study was to determine the effects of mechanical vibr ation loading on DNA and proteoglycan syntheses in cultured rabbit articula r chondrocytes. Chondrocyte culture plates were placed in a vibratory appar atus and subjected to a mechanical vibratory load at various frequencies an d periods in culture. Mechanical vibration was applied at a sinusoidal wave form of 1.4 g acceleration with frequencies of 200, 300, 400, 800, and 1600 Hz. H-3-Thymidine and (H2SO4)-S-35 incorporation were used to detect radio labeled DNA and proteoglycan syntheses, respectively. A frequency of 300 Hz showed a time-dependent augmentation of DNA synthesis and gave a maximal i ncrease at day 3 with periodic vibration (8 h per day) and at 72 h or longe r with continuous vibration. It also promoted proteoglycan synthesis in lon g-term culture (from 3 to 15 days) by periodic vibration. However, frequenc ies above 400 Hz suppressed biosynthesis. These results suggest that mechan ical vibration at: certain frequencies may modulate biosynthetic response o f articular chondrocytes.