title: The biological action of hyaluronan on human osteoartritic articular chondrocytes: the importance of molecular weight.
abstract: OBJECTIVE
  The intra-articular injection of hyaluronan (HA) was originally used in the treatment of osteoarthritis (OA) to increase the viscosity of synovial fluid. However, some findings suggest that the activity of HA cannot be solely explained by its biomechanical properties. The aim of this study was to analyze the in vitro biological effects of HA on human OA chondrocytes and the impact of its molecular weight (MW) on those effects.
  
  
  METHODS
  Cells were isolated from cartilage obtained during joint replacement surgery in OA patients. The chondrocytes were cultured for 24 hours to detect prostaglandin E2 (PGE2) and for 48 hours to measure nitric oxide (NO), after which they were pre-incubated with HA and stimulated with interleukin-1 (IL-1) at 5 ng/ml. Two commercial HA preparations with different MWs were used: Hyalgan (500-730 kDa, HA, Bioibérica S.A.) and Synvisc (hylan of 6,000 kDa, Biomatrix Inc). NO was detected by the Greiss reaction and PGE2 was quantified by a commercial EIA in the supernatant. Apoptosis was induced by an NO donor (sodium nitroprusside, SNP) and the effect of HA on apoptosis was quantified by flow cytometry.
  
  
  RESULTS
  Neither HA preparation studied had any effect on the basal production of NO or PGE2. However, the 500-730 kDa HA at 200 microg/ml reduced the synthesis of both IL-1-induced NO and PGE2 by 70% and 45% respectively. Furthermore both HA preparations at 200 microg/ml decreased the apoptosis induced by SNP, 500-730 kDa to 40% and 6,000 kDa to 36%.
  
  
  CONCLUSIONS
  HA may induce biological effects in addition to acting as a viscoelastic substance. This study suggests that HA preparations are different due to differences in biological activity resulting from MW.
authors.affiliation: Laboratory of Investigation, Rheumatology Division, CHU Juan Canalejo, A Coruña, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Maneiro
authors.forename: M C
authors.initials: MC
authors.lastname: de Andres
authors.forename: J L
authors.initials: JL
authors.lastname: Fernández-Sueiro
authors.forename: F
authors.initials: F
authors.lastname: Galdo
authors.forename: F J
authors.initials: FJ
authors.lastname: Blanco
mesh_terms: D000276:Adjuvants, Immunologic / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002358:Cartilage, Articular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D006820:Hyaluronic Acid / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism; D010003:Osteoarthritis
chemical_list: D000276:Adjuvants, Immunologic; D007375:Interleukin-1; D009569:Nitric Oxide; D006820:Hyaluronic Acid; D015232:Dinoprostone