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Cyclic loading inhibits expression of MMP-3 but not MMP-1in an in vitro rabbit flexor tendon model.

Authors
Asundi-KR; Rempel-DM
Source
Clin Biomech 2008 Jan; 23(1):117-121
NIOSHTIC No.
20037280
Abstract
Background. Gene expression analysis is useful for assessing cellular behavior and may improve our understanding of the initial cellular response to mechanical load leading to tendon degeneration. This study assessed gene expression of MMP-1 and MMP-3, genes associated with matrix degradation, in tendons exposed to cyclic loads within physiologic range. Methods. Six flexor tendons from each of ten New Zealand White rabbits were harvested and randomly assigned to one of the following six groups: load deprived for 18 h; cyclically loaded for 18 h to a peak stress of 2 MPa; 3 MPa; 4 MPa; 5 MPa; or snap frozen in liquid nitrogen. MMP-1, MMP-3 and 18 s mRNA expression was measured by qRT-PCR. Findings. No significant differences in MMP-1 mRNA expression levels were found between loading groups. MMP-3 expression was significantly inhibited (57%) in tendons cyclically loaded to a peak stress of 4 MPa in comparison to load deprived tendons, however, when peak stress was increased to 5 MPa, expression was no longer significantly lower compared to stress shielded tendons. Interpretation. The results suggest a 'U' shape relationship between load and MMP-3 expression. The lack of change in MMP-1 expression with loading was unexpected as inhibition of MMP-1 in response to mechanical load has been demonstrated in previous studies. In conclusion, we demonstrate that MMP-3 expression is modulated by cyclic load and is sensitive to load magnitude. MMP-1 mRNA expression is not significantly modulated by cyclic load in this model.
Keywords
Biological-effects; Biological-function; Biomechanical-engineering; Biomechanical-modeling; Biomechanics; Cell-biology; Cellular-reactions; Control-technology; Engineering; Engineering-controls; Ergonomics; Exposure-assessment; Exposure-levels; Exposure-methods; Genetic-factors; Injury-prevention; Laboratory-animals; Laboratory-testing; Mechanics; Musculoskeletal-system; Musculoskeletal-system-disorders; Neurological-reactions; Physiological-effects; Physiological-measurements; Physiological-response; Quantitative-analysis; Repetitive-work; Risk-analysis; Risk-factors; Statistical-analysis; Author Keywords: Tendinopathy; Overuse injury; Organ culture; Dynamic tissue loading; Matrix metalloproteinase
Contact
Dr. David Rempel, Department of Bioengineering, University of California, Berkeley, 1301 South 46th Street, Building 163, Richmond, CA 94804
CODEN
CLBIEW
Publication Date
20080101
Document Type
Journal Article
Email Address
david.rempel@ucsf.edu
Funding Type
Grant
Fiscal Year
2008
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-T42-OH-008429
Issue of Publication
1
ISSN
0268-0033
Source Name
Clinical Biomechanics
State
CA
Performing Organization
University of California, Berkeley
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