Synergistic effects of heating and traction during fibrous tissue elongation

Fibrosis involves the abnormal accumulation of components of the extracellular matrix, such as collagen, and can lead to organ failure, which accounts for approximately one-third of all deaths worldwide. Accordingly, there is an urgent need to develop low-invasive treatment strategies for fibrosis as there is currently a lack of anti-fibrotic pharmacological agents available. In the present study, we tested the hypothesis that applying traction to fibrous tissues while using heat to denature proteins can be used to adjust the shape and flexibility of tissues. Bovine Achilles tendon samples as a model of fibrous tissue contracted by approximately 25% compared to the original length in response to heating, in line with previous findings. In contrast, the application of traction during heating and cooling increased tissue length by 25% and decreased Young’s modulus by 16%. Tissue staining and detection of unfolded collagen using collagen-hybridizing peptide demonstrated thermal degradation of collagen fibers and conversion to gelatinous material throughout samples, confirming that traction, and heating damages collagen. These results indicate that this technique can be used to alter the shape and reduce the rigidity of organs affected by fibrosis.