title: Glucosamine reduces anabolic as well as catabolic processes in bovine chondrocytes cultured in alginate.
abstract: OBJECTIVE
  To investigate the working mechanism of glucosamine (GlcN) by studying the effect of different GlcN derivatives on bovine chondrocytes in alginate beads under anabolic and catabolic culture conditions.
  
  
  METHODS
  Bovine chondrocytes seeded in alginate beads were treated with different concentrations of glucosamine-sulfate (GlcN-S), glucosamine-hydrochloride (GlcN-HCl) or N-acetyl-glucosamine (GlcN-Ac). Culture conditions were anabolic, 3 day pre-culture followed by 14 days' treatment; catabolic, extracellular matrix (ECM) breakdown induced by 10ng/ml interleukin-1beta (IL-1beta); or a situation with balance between ECM breakdown and synthesis, 24 days' pre-culture followed by 14 days' treatment. The outcome measurements were total glycosaminoglycan (GAG) and DNA content per bead.
  
  
  RESULTS
  In the situation with balance between ECM breakdown and synthesis, GlcN-Ac had a small stimulatory effect on total GAG content. GlcN-S and GlcN-HCl had no effect. Under anabolic condition 5mM GlcN-S and GlcN-HCl significantly reduced total GAG content. GlcN-Ac did not show this effect. IL-1beta induced catabolic effects were prevented by adding 5mM GlcN-HCl. Interference of GlcN with glucose (Gluc) was demonstrated by adding extra Gluc to the medium in the anabolic culture conditions. Increasing extracellular Gluc concentrations diminished the effect of GlcN.
  
  
  CONCLUSIONS
  GlcN-S and GlcN-HCl, but not GlcN-Ac, reduce anabolic and catabolic processes. For anabolic processes this was demonstrated by decreased ECM synthesis, for catabolic processes by protection against IL-1beta mediated ECM breakdown. This might be due to interference of GlcN with Gluc utilization. We suggest that the claimed structure modifying effects of GlcN are more likely based on protection against ECM degradation than new ECM production.
authors.affiliation: Department of Orthopaedics, Erasmus MC, University Medical Center Rotterdam, 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: S M A
authors.initials: SM
authors.lastname: Bierma-Zeinstra
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: D000464:Alginates; D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D020723:Glucuronic Acid; D006025:Glycosaminoglycans / Q000378:metabolism*; D006603:Hexuronic Acids
chemical_list: D000464:Alginates; D006025:Glycosaminoglycans; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D005944:Glucosamine