Tendon cell ciliary length as a biomarker of in situ cytoskeletal tensional homeostasis

To determine if tendon cell ciliary length could be used as a biomarker of cytoskeletal tensional homeostasis, 20 mm long adult rat tail tendons were placed in double artery clamps set 18 mm apart to create a 10% laxity. The tendons were allowed to contract over a 7 day period under culture conditions. At 0, 1, 5, and 7 days the tendon cell cilia were stained and ciliary length measured using confocal imaging. There was a significant (p<0.001) increase in ciliary length at 1 day. At day 5 (when the tendon became visibly taut) there was a significant (p<0.001) decrease in ciliary length compared to day 1. By day 7 the tendon remained taut and ciliary length returned to day zero values (p=0.883). These results suggest that cilia length reflects the local mechanobiological environment of tendon cells and could be used as a potential in situ biomarker of altered cytoskeletal tensional homeostasi