Abstract
It was aimed to investigate the isolated effect of hydrostatic pressure on chondrocyte metabolism. Chondrocytes obtained from bovine metatarso-phalangeal joints were cultured in cylindrical 2% agarose gels. A special apparatus which was designed and constructed, allowed the application of hydrostatic pressure of either 2 MPa or 5 MPa on the chondrocytes for 4 hours either in a pulsatile (1Hz) or a static manner. Changes in the syntheses of glycosaminoglycan (GAG) and DNA during and after the application of the hydrostatic pressure were analysed with 35S-sulphate and 3H-thymidine incorporation, respectively. Radiolabelling was carried out for the following conditions: (a) 4 hours during the application of hydrostatic pressure; (b) 4 hours and (c) 20 hours immediately after the application of load. In addition, the experiments were carried out at 2 days, 7 days and 14 days after embedding the chondrocytes in agarose gels. Static hydrostatic pressure of 5 MPa caused a significant increase by 13% on average in the GAG synthesis during the load application on Day 2 7 and 14 (p < 0.05). On the contrary, pulsatile pressure of 2 MPa caused a significant decrease by 17% in the GAG synthesis measured at 20 hours after the loading on Day 14 (p < 0.01). In addition, there was a significant decrease by 29% in the DNA synthesis measured at 4 hours after the pulsatile loading of 5 MPa on Day 7 (p < 0.01). The results suggest that hydrostatic pressure alone, which causes no cell deformation, can affect the GAG synthesis and proliferation of chondrocytes. In addition, the effect of hydrostatic pressure on the chondrocyte metabolism varies according to the regimes of loading and with the period of cell culture.
*The authors would like to acknowledge the Wellcome Trust for their financial support.
The abstracts were prepared by Mr Simon Donell. Correspondence should be addressed to him at the Department of Orthopaedics, Norfolk & Norwich Hospital, Level 4, Centre Block, Colney Lane, Norwich NR4 7UY, United Kingdom.
