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Cycle‐dependent matrix remodeling gene expression response in fatigue‐loaded rat patellar tendons
Author(s) -
Sun Hui B.,
AndarawisPuri Nelly,
Li Yonghui,
Fung David T.,
Lee Jonathan Y.,
Wang Vincent M.,
BastaPljakic Jelena,
Leong Daniel J.,
Sereysky Jedd B.,
Ros Stephen J.,
Klug Raymond A.,
Braman Jonathan,
Schaffler Mitch B.,
Jepsen Karl J.,
Flatow Evan L.
Publication year - 2010
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.21132
Subject(s) - downregulation and upregulation , matrix metalloproteinase , tendon , gene expression , patellar tendon , extracellular matrix , microbiology and biotechnology , medicine , chemistry , pathology , biology , gene , biochemistry
Expression profiling of selected matrix remodeling genes was conducted to evaluate differences in molecular response to low‐cycle (100) and high‐cycle (7,200) sub‐failure‐fatigue loading of patellar tendons. Using our previously developed in vivo patellar tendon model, tendons were loaded for 100 or 7,200 cycles and expression of selected metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and collagens were quantified by real‐time RT‐PCR at 1‐ and 7‐day post‐loading. Expression profiles were also obtained from lacerated tendons as an acute injury model. The high‐cycle group showed upregulation of TIMP‐1, ‐2, Col3a1, and Col5a1, and downregulation TIMP‐4 at both time points, upregulation of MMP‐2 at 7‐day post‐loading and downregulation of MMP‐13 and ‐14 at 1‐day post‐loading, suggesting overall repair/remodeling. In contrast, the low‐cycle loaded group showed upregulation of MMP‐2, ‐3, ‐13, and Col12a1 at both time points, upregulation of TIMP‐1, ‐2, ‐3, Col3a1, and integrin β1 and downregulation of integrin α11 at 1‐day post‐loading and upregulation of Col1a1 at 7‐day post‐loading, consistent with a hypertrophic (adaptive) pattern. Lacerated tendons showed a typical acute wound response with upregulation of all examined remodeling genes. Differences found in tendon response to high‐ and low‐cycle loading are suggestive of the underlying mechanisms associated with a healthy or damaging response. Published by Wiley Periodicals, Inc. J Orthop Res 28:1380–1386, 2010