Bending-Induced Strain Delays Collagen Degradation by Collagenase

Abstract

Collagen is the predominant structural protein in mammals and is most abundant in stiff, solid tissues that sustain mechanical stress. Some studies have suggested tension can stabilize fibers against degradation independent of cell activity. Here, strain gradients were generated in isolated tendon fascicle using three-point bending, with patterned photo-bleaching of fluorescent tendon used to measure strain. Deformed fascicle was exposed to collagenase, and degradation was tracked using Second Harmonic Generation (SHG) signal produced by fibrillar collagen. Importantly, mechanical strains up to 5∼8% magnitude maximize collagen fibril lifetime when exposed to collagenase. Fluorescent dextran permeation of the tendon further showed relatively uniform density, while Fluorescence Recovery after Photobleaching (FRAP) revealed strain dependent increase in mobility. Applied mechanical strain preserves collagen fibrils in tissue in the presence of collagenase. Our results have the potential to deepen the understanding of collagen matrices in development, adaptation, and disease.