Submitted on July 6, 2005
Accepted on June 19, 2006
AGE-DEPENDENT CHANGES IN THE MECHANICAL PROPERTIES OF TAIL TENDONS IN TGF
INDUCIBLE EARLY GENE-1 (TIEG) KNOCKOUT MICE
sabine bensamoun1, Tetsu Tsubone2, Malayannan Subramaniam3, John R Hawse3, Emir Boumediene1, Thomas C. Spelsberg3, Kai-Nan An1, and peter C Amadio1*
1 Department of Orthopedics, Mayo Clinic, Rochester, Minnesota, United States
2 orthopedics, Mayo Clinic, Rochester, Minnesota, United States
3 Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States
* To whom correspondence should be addressed. E-mail: amadio.peter{at}mayo.edu.
The purpose of this study is to investigate age-dependent changes in the architecture and mechanical properties of tendon in TGF
Inducible Early Gene-1 (TIEG) knockout mice. Wild-type and TIEG knockout mice, aged one, three, and fifteen months, were used. The mechanical properties of tail tendons isolated from these mice were determined using uniaxial tensile ramp (0.05mm/s) and relaxation (5mm/s) tests, with a strain of 10%. Mechanical parameters (Young's modulus from the ramp test; fast and static stresses from the relaxation test) were measured and recorded. The structure of the tail tendon fascicle was characterized by transmission electron microscopy. The results of the mechanical testing revealed no significant difference between the knockout and wild-type groups at 1 or 15 months of age. However, the fascicles of the knockout mice at 3 months of age exhibited decreased fast and static stresses than those of the wild-type mice. Electronmicroscopy revealed an increase in fibril size in the knockout mouse tendons relative to wild-type controls at 1 and 3 months of age. These data indicate an important role for TIEG in tendon microarchitecture and strength in adult mice.
