title: Meniscal tissue explants response depends on level of dynamic compressive strain.
abstract: OBJECTIVE
  Following partial meniscectomy, the remaining meniscus is exposed to an altered loading environment. In vitro 20% dynamic compressive strains on meniscal tissue explants has been shown to lead to an increase in release of glycosaminoglycans from the tissue and increased expression of interleukin-1alpha (IL-1alpha). The goal of this study was to determine if compressive loading which induces endogenously expressed IL-1 results in downstream changes in gene expression of anabolic and catabolic molecules in meniscal tissue, such as MMP expression.
  
  
  METHODS
  Relative changes in gene expression of MMP-1, MMP-3, MMP-9, MMP-13, A Disintegrin and Metalloproteinase with ThromboSpondin 4 (ADAMTS4), ADAMTS5, TNFalpha, TGFbeta, COX-2, Type I collagen (COL-1) and aggrecan and subsequent changes in the concentration of prostaglandin E(2) released by meniscal tissue in response to varying levels of dynamic compression (0%, 10%, and 20%) were measured. Porcine meniscal explants were dynamically compressed for 2h at 1Hz.
  
  
  RESULTS
  20% dynamic compressive strains upregulated MMP-1, MMP-3, MMP-13 and ADAMTS4 compared to no dynamic loading. Aggrecan, COX-2, and ADAMTS5 gene expression were upregulated under 10% strain compared to no dynamic loading while COL-1, TIMP-1, and TGFbeta gene expression were not dependent on the magnitude of loading.
  
  
  CONCLUSIONS
  This data suggests that changes in mechanical loading of the knee joint meniscus from 10% to 20% dynamic strain can increase the catabolic activity of the meniscus.
authors.affiliation: Biotechnology Research Center, Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49931, United States.
authors.forename: B
authors.initials: B
authors.lastname: Zielinska
authors.forename: M
authors.initials: M
authors.lastname: Killian
authors.forename: M
authors.initials: M
authors.lastname: Kadmiel
authors.forename: M
authors.initials: M
authors.lastname: Nelsen
authors.forename: T L
authors.initials: TL
authors.lastname: Haut Donahue
mesh_terms: D000818:Animals; D017364:Collagenases / Q000235:genetics / Q000378:metabolism*; D019245:Compressive Strength; D015870:Gene Expression / Q000235:genetics; D007719:Knee Joint / Q000378:metabolism*; D008592:Menisci, Tibial / Q000473:pathology*; D020370:Osteoarthritis, Knee / Q000235:genetics / Q000473:pathology*; D013314:Stress, Mechanical; D013552:Swine; D000070600:Tibial Meniscus Injuries; D015854:Up-Regulation; D016474:Weight-Bearing
chemical_list: D017364:Collagenases