title: Glucosamine decreases expression of anabolic and catabolic genes in human osteoarthritic cartilage explants.
abstract: OBJECTIVE
  To investigate the effect of glucosamine (GlcN) in a human osteoarthritic explant model on expression of genes involved in anabolic and catabolic activities of chondrocytes.
  
  
  METHODS
  Human osteoarthritic explants, obtained during knee arthroplasty surgery, were pre-cultured (3 days) and treated with glucosamine-hydrochloride (GlcN-HCl) or glucosamine-3-sulphate (GlcN-S) at 0.5mM and 5mM (4 days). RNA was isolated from the explants and real time RT-PCR was performed. Additionally, total matrix metalloproteinase (MMP) activity was measured in culture medium.
  
  
  RESULTS
  Addition of 5mM GlcN led to significant down-regulation of aggrecan (2.65-7.73-fold) and collagen type II (7.75-22.17-fold) gene expression, indicating inhibited anabolic activity. Considering catabolic activities, 5mM GlcN significantly down-regulated aggrecanase-1 and MMP3 and 5mM GlcN-S additionally down-regulated aggrecanase-2 and tissue inhibitor of MMP gene expression significantly. Gene expression was not significantly altered by 0.5mM GlcN. Total MMP activity in culture medium was only significantly reduced after addition of 5mM GlcN-HCl.
  
  
  CONCLUSIONS
  The effects of GlcN on gene expression in a human osteoarthritic explant model suggest that enzymatic breakdown of the extra-cellular matrix might be reduced by the addition of 5mM GlcN. Additionally, restoration of already damaged cartilage is not to be expected, because gene expression of anabolic genes is also down-regulated. We suggest that chondroprotective properties of GlcN in vivo may be based on inhibiting further degradation due to catabolic activities, rather than on the ability to rebuild cartilage.
authors.affiliation: Erasmus MC, University Medical Center Rotterdam, Department of Orthopaedics, The Netherlands.
authors.forename: E J
authors.initials: EJ
authors.lastname: Uitterlinden
authors.forename: H
authors.initials: H
authors.lastname: Jahr
authors.forename: J L M
authors.initials: JL
authors.lastname: Koevoet
authors.forename: Y M
authors.initials: YM
authors.lastname: Jenniskens
authors.forename: S M A
authors.initials: SM
authors.lastname: Bierma-Zeinstra
authors.forename: J
authors.initials: J
authors.lastname: Degroot
authors.forename: J A N
authors.initials: JA
authors.lastname: Verhaar
authors.forename: H
authors.initials: H
authors.lastname: Weinans
authors.forename: G J V M
authors.initials: GJ
authors.lastname: van Osch
mesh_terms: D000368:Aged; D053674:Aggrecans; D002358:Cartilage, Articular / Q000187:drug effects* / Q000378:metabolism; D011508:Chondroitin Sulfate Proteoglycans / Q000096:biosynthesis / Q000235:genetics; D024043:Collagen Type II / Q000096:biosynthesis / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects*; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis / Q000235:genetics; D005944:Glucosamine / Q000494:pharmacology*; D006801:Humans; D037181:Lectins, C-Type / Q000096:biosynthesis / Q000235:genetics; D020782:Matrix Metalloproteinases / Q000096:biosynthesis / Q000235:genetics; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000378:metabolism* / Q000473:pathology; D046509:Tissue Culture Techniques; D019714:Tissue Inhibitor of Metalloproteinases / Q000096:biosynthesis / Q000235:genetics
chemical_list: D053674:Aggrecans; D011508:Chondroitin Sulfate Proteoglycans; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type; D019714:Tissue Inhibitor of Metalloproteinases; D020782:Matrix Metalloproteinases; D005944:Glucosamine