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Mechanical overload decreases the thermal stability of collagen in an in vitro tensile overload tendon model
Author(s) -
Willett Thomas L.,
Labow Rosalind S.,
Lee J. Michael
Publication year - 2008
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.20672
Subject(s) - tendon , ultimate tensile strength , denaturation (fissile materials) , biophysics , differential scanning calorimetry , strain rate , strain (injury) , soft tissue , in vitro , chemistry , materials science , anatomy , composite material , medicine , biochemistry , pathology , biology , thermodynamics , physics , nuclear chemistry
Musculoskeletal soft tissue injuries are very common, yet poorly understood. We investigated molecular‐level changes in collagen caused by tensile overload of bovine tail tendons in vitro. Previous investigators concluded that tensile tendon rupture resulted in collagen denaturation, but our study suggests otherwise. Based on contemporary collagen biophysics, we hypothesized that tensile overload would lead to reduced thermal stability without change in the nativity of the molecular conformation. The thermal behavior of collagen from tail tendons ruptured in vitro at two strain rates (0.01 s −1 and 10 s −1 ) was measured by differential scanning calorimetry (DSC). The 1,000‐fold difference in strain rate was used since molecular mechanisms that determine mechanical behavior are thought to be strain rate‐dependent. DSC revealed that the collagen in tensile overloaded tendons was less thermally stable by 3° to 5°C relative to undamaged controls and was not denatured since there was no change in enthalpy of denaturation. The decrease in thermal stability occurred throughout the overloaded regions, independent of rupture site, and was greater in specimens ruptured at the lower strain rate. The deformation mechanism apparently involves disruption of the lattice structure of the collagen fibrils and greatly increases the molecular freedom of the collagen molecules, leading to reduced thermal molecular stability and the previously reported increased proteolysis. This has important implications for understanding soft tissue injuries, disease etiology and treatment, and for developing tissue engineered products with improved durability. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res