title: Glucosamine modulates chondrocyte proliferation, matrix synthesis, and gene expression.
abstract: OBJECTIVE
  To investigate the effects of glucosamine (GlcN) on chondrocyte proliferation, matrix production, and gene expression for providing insights into the biochemical basis of its reported beneficial effects in osteoarthritis (OA).
  
  
  METHODS
  Dose-dependent effect of GlcN on cell morphology, proliferation, cartilage matrix production and gene expression was examined by incubating primary bovine chondrocytes with various amounts of GlcN in monolayers (2D) and in cell-laden hydrogels (3D constructs). Histology, immunofluorescent staining and biochemical analyses were used to determine the effect of GlcN on cartilage matrix production in 3D constructs. The impact of GlcN on gene expression was evaluated with real-time polymerase chain reaction (PCR).
  
  
  RESULTS
  GlcN concentration and culture conditions significantly affected the cell behavior. Quantitative detection of matrix production in cell-laden hydrogels indicated a relatively narrow window of GlcN concentration that promotes matrix production (while limiting cellular proliferation, but not cell viability). Notably, GlcN enhanced cartilage specific matrix components, aggrecan and collagen type II, in a dose-dependent manner up to 2 mM but the effect was lost by 15 mM. Additionally, GlcN treatment up-regulated transforming growth factor-beta1 (TGF-beta1) mRNA levels.
  
  
  CONCLUSIONS
  Results indicate that culture conditions play a significant role in determining the effect of GlcN on chondrocytes, explaining both the previously reported beneficial and deleterious effects of this sugar. The ability of GlcN to alter TGF-beta1 signaling provides a biochemical mechanism for GlcN activity on chondrocytes that up to now has remained elusive. The observed anabolic effect of optimal GlcN concentrations on chondrocytes may be useful in formulating effective cartilage repair strategies.
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21218, USA.
authors.forename: S
authors.initials: S
authors.lastname: Varghese
authors.forename: P
authors.initials: P
authors.lastname: Theprungsirikul
authors.forename: S
authors.initials: S
authors.lastname: Sahani
authors.forename: N
authors.initials: N
authors.lastname: Hwang
authors.forename: K J
authors.initials: KJ
authors.lastname: Yarema
authors.forename: J H
authors.initials: JH
authors.lastname: Elisseeff
mesh_terms: D053674:Aggrecans; D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology*; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects*; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects*; D005109:Extracellular Matrix / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects; D005944:Glucosamine / Q000494:pharmacology*; D020100:Hydrogels; D016133:Polymerase Chain Reaction
chemical_list: D053674:Aggrecans; D020100:Hydrogels; D005944:Glucosamine