title: Influence of repetitive mechanical loading on MMP2 activity in tendon fibroblasts.
abstract: Matrix metalloproteinase2 has been implicated in tendon pathology caused by repetitive movements. However, its activity in the early stages of the tendon's response to overuse, and its presence in the circulation as a possible indicator of tendon degradation, remain unknown. Human tendon cells were repetitively stretched for 5 days, and the rabbit Achilles tendon complex underwent repetitive motion 3× per week for 2 weeks. Quantitative polymer chain reaction analysis was performed to detect matrix metalloproteinase2/14 and tissue inhibitor of matrix metalloproteinase2 messenger ribonucleic acid of cells and rabbit tissue, and matrix metalloproteinase2 protein levels were determined with an enzyme linked immunoassay. Matrix metalloproteinase2 activity was examined using zymography of the conditioned media, tendon and serum. Immunohistochemistry was used to localize matrix metalloproteinase2 in tendon tissue, and the density of fibrillar collagen in tendons was examined using second harmonic generation microscopy. Tendon cells stretched with high strain or high frequency demonstrated increased matrix metalloproteinase2 messenger ribonucleic acid and protein levels. Matrix metalloproteinase2 activity was increased in the rabbit Achilles tendon tissue at weeks 1 and 2; however, serum activity was only increased at week 1. After 2 weeks of exercise, the collagen density was lower in specific regions of the exercised rabbit Achilles tendon complex. Matrix metalloproteinase2 expression in exercised rabbit Achilles tendons was detected surrounding tendon fibroblasts. Repetitive mechanical stimulation of tendon cells results in a small increase in matrix metalloproteinase2 levels, but it appears unlikely that serum matrix metalloproteinase2 will be a useful indicator of tendon overuse injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1991-2000, 2016.
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, Canada.|Centre for Hip Health and Mobility, Vancouver Coastal Health and Research Institute, Vancouver, Canada.
authors.forename: Elise
authors.initials: E
authors.lastname: Huisman
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, Canada.|Centre for Hip Health and Mobility, Vancouver Coastal Health and Research Institute, Vancouver, Canada.
authors.forename: Alex
authors.initials: A
authors.lastname: Lu
authors.affiliation: Centre for Hip Health and Mobility, Vancouver Coastal Health and Research Institute, Vancouver, Canada.
authors.forename: Sarwat
authors.initials: S
authors.lastname: Jamil
authors.affiliation: Centre for Hip Health and Mobility, Vancouver Coastal Health and Research Institute, Vancouver, Canada.
authors.forename: Rouhollah
authors.initials: R
authors.lastname: Mousavizadeh
authors.affiliation: Department of Orthopaedic Surgery, University of British Columbia, Vancouver, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: McCormack
authors.affiliation: Department of Dentistry, University of British Columbia, Vancouver, Canada.
authors.forename: Clive
authors.initials: C
authors.lastname: Roberts
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, Canada.|Centre for Hip Health and Mobility, Vancouver Coastal Health and Research Institute, Vancouver, Canada.
authors.forename: Alex
authors.initials: A
authors.lastname: Scott
mesh_terms: D000125:Achilles Tendon / Q000201:enzymology / Q000473:pathology; D000818:Animals; D015415:Biomarkers / Q000097:blood; D002478:Cells, Cultured; D012090:Cumulative Trauma Disorders / Q000097:blood / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000097:blood*; D011817:Rabbits; D013314:Stress, Mechanical; D052256:Tendinopathy / Q000097:blood / Q000201:enzymology* / Q000473:pathology; D000070916:Tenocytes / Q000201:enzymology*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D016474:Weight-Bearing
chemical_list: D015415:Biomarkers; D019716:Tissue Inhibitor of Metalloproteinase-2; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14
keywords: matrix metalloproteinase; mechanical stimulation; overuse; tendon