Effect of Intermittent Cyclic Tensile Strain on Collagen Synthesis by Tenocytes in Isolated Fascicles

Intermittent pattern of mechanical stimulation has been demonstrated to possess different regulatory effects on cell metabolism in many connective tissues, but little is known about tenocyte responses. A previous study has shown that the application of a small number of continuous cyclic strain inhibited collagen synthesis by tenocytes in explants, whereas a large number of strain cycles upregulated the synthesis. Thus, the present study tested the hypothesis that collagen synthesis is influenced by cyclic tensile strain provided in an intermittent manner. A total of 43,200 cycles of tensile strain, with a 3% amplitude superimposed on a 2% static strain was provided in four different intermittent patterns with different strain/unstrain periods: 10 minutes, 1 hour, 6 hours, and 12 hours. The amount of newly synthesised collagen, both those retained in strained fascicles and released into culture media, were not significantly altered by the application of different patters of intermittent cyclic strain. The present findings may suggest that, unlike other connective tissue cells, tenocyte responses are predominantly regulated by the total number of strain cycles.