Tenocyte anabolic and catabolic response to elevation in intracellular tension

The present study examined expressions of type I collagen and MMP-1 mRNA of bovine tenocytes in response to elevation in intracellular tension/traction forces induced by either mechanical or chemical stimulation. Tenocytes were cultured in the following conditions: micropillars with the Young’s modulus of 75 kPa in a normal culture medium, in the presence of 1 nM calyculin A in the medium or under 4 or 8% static tensile strain in the normal medium. In all the treatments, cell traction forces were increased significantly from the levels of corresponding control tenocytes. However, these increases in traction forces were not associated with statistically significant increase in type I collagen gene expression. Because our treatments induced the increase in traction forces equidirectionally, it is speculated that highly directional increase in traction forces, associated with an elongated cell shape, is required to induce marked upregulation of type I collagen mRNA expression in tenocytes.