The mechanosensitivity of cartilage oligomeric matrix protein (COMP).

Physical forces are known to influence the synthesis, assembly and degradation of the cartilage extracellular matrix. The expression of cartilage oligomeric matrix protein (COMP) was found to be sensitive to long term cyclic compression. Explants of calf articular cartilage as well as cylindrical alginate/chondrocyte constructs were subjected to uniaxial unconfined dynamic compression for 18 hours after which total mRNA was extracted from samples. COMP expression was assessed by means of semi-quantitative RT-PCR and Northern blot techniques. The COMP transcript was found to be significantly enriched upon compression in both experimental systems. Incubation with anti-beta1 integrin blocking antibodies abolished the mechanosensitivity of COMP expression. In addition, the presence of a fully developed pericellular matrix was shown to be a prerequisite for enhanced COMP expression with cyclic loading. Cell/matrix interactions are therefore one of the key events in mechanotransduction in chondrocytes.