Cartilage tissue remodeling in response to mechanical forces

Recent studies suggest that there are multiple regulatory pathways by which chondrocytes in articular cartilage sense and respond to mechanical stimul i, including upstream signaling pathways and mechanisms that may lead to di rect changes at the level of transcription, translation, post-translational modifications, and cell-mediated extracellular assembly and degradation of the tissue matrix. This review focuses on the effects of mechanical loadin g on cartilage and the resulting chondrocyte-mediated biosynthesis, remodel ing, degradation, and repair of this tissue. The effects of compression and tissue shear deformation are compared, and approaches to the study of mech anical regulation of gene expression are described. Of particular interest regarding dense connective tissues, recent experiments have shown that mech anotransduction is critically important in vivo in the cell-mediated feedba ck between physical stimuli, the molecular structure of newly synthesized m atrix molecules, and the resulting macroscopic biomechanical properties of the tissue.