Effect of altered matrix proteins on quasilinear viscoelastic properties in transgenic mouse tail tendons.
Tendons have complex mechanical behaviors that are viscoelastic, nonlinear, and anisotropic. It is widely held that these behaviors are provided for by the tissue's composition and structure. However, little data are available to quantify such structure-function relationships. This study quantified tendon mechanical behaviors, including viscoelasticity and nonlinearity, for groups of mice that were genetically engineered for altered extracellular matrix proteins. Uniaxial tensile stress-relaxation experiments were performed on tail tendon fascicles from the following groups: eight week old decorin knockout, eight week old reduced type I collagen, three week old control, and eight week old control. Data were fit using Fung's quasilinear viscoelastic model, where the model parameters represent the linear viscoelastic and nonlinear elastic response. The viscoelastic properties demonstrated a larger and faster stress relaxation for the decorin knockout and a smaller and slower stress relaxation for the three week control. The elastic parameter, A, in the eight week control group was significantly greater than in the collagen reduction and three week control groups. This study provides quantitative evidence for structure-function relationships in tendon, including the role of proteoglycan in viscoelasticity. Future studies should directly correlate composition and structure with tendon mechanics for the design and evaluation of tissue-engineered constructs or tendon repairs.
Elliott
Dawn M
DM
McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104-6081, USA. delliott@mail.med.upenn.edu
Robinson
Paul S
PS
Gimbel
Jonathan A
JA
Sarver
Joseph J
JJ
Abboud
Joseph A
JA
Iozzo
Renato V
RV
Soslowsky
Louis J
LJ
D000818:Animals; D030801:Animals, Genetically Modified / Q000502:physiology; D024042:Collagen Type I / Q000172:deficiency / Q000502:physiology; D003198:Computer Simulation; D046508:Culture Techniques; D058575:Decorin; D004548:Elasticity; D005109:Extracellular Matrix / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice / Q000235:genetics; D008954:Models, Biological; D017711:Nonlinear Dynamics; D011509:Proteoglycans / Q000172:deficiency / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013623:Tail / Q000502:physiology; D013710:Tendons / Q000166:cytology / Q000502:physiology*; D013718:Tensile Strength; D014783:Viscosity
D024042:Collagen Type I; C546879:Dcn protein, mouse; D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans