title: Synoviocytes protect cartilage from the effects of injury in vitro.
abstract: BACKGROUND
  It is well documented that osteoarthritis (OA) can develop following traumatic joint injury and is the leading cause of lameness and subsequent wastage of equine athletes. Although much research of injury induced OA has focused on cartilage, OA is a disease that affects the whole joint organ.
  
  
  METHODS
  In this study, we investigated the impact of synovial cells on the progression of an OA phenotype in injured articular cartilage. Injured and control cartilage were cultured in the presence of synoviocytes extracted from normal equine synovium. Synoviocytes and cartilage were evaluated for catabolic and anabolic gene expression. The cartilage was also evaluated histologically for loss of extracellular matrix molecules, chondrocyte cell death and chondrocyte cluster formation.
  
  
  RESULTS
  The results indicate synoviocytes exert both positive and negative effects on injured cartilage, but ultimately protect injured cartilage from progressing toward an OA phenotype. Synoviocytes cultured in the presence of injured cartilage had significantly reduced expression of aggrecanase 1 and 2 (ADAMTS4 and 5), but also had increased expression of matrix metalloproteinase (MMP) -1 and reduced expression of tissue inhibitor of metalloproteinases 1 (TIMP-1). Injured cartilage cultured with synoviocytes had increased expression of both collagen type 2 and aggrecanase 2. Histologic examination of cartilage indicated that there was a protective effect of synoviocytes on injured cartilage by reducing the incidence of both focal cell loss and chondrocyte cluster formation, two major hallmarks of OA.
  
  
  CONCLUSIONS
  These results support the importance of evaluating more than one synovial joint tissue when investigating injury induced OA.
authors: Orthopaedic Research Center, Department of Clinical Sciences, College of Veterinary Medicine, Colorado State University, 300 West Drake Rd,, Fort Collins, Colorado CO 80523, USA.
authors: Christina M
authors: CM
authors: Lee
authors: John D
authors: JD
authors: Kisiday
authors: C Wayne
authors: CW
authors: McIlwraith
authors: Alan J
authors: AJ
authors: Grodzinsky
authors: David D
authors: DD
authors: Frisbie
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000293:injuries*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000502:physiology; D018920:Coculture Techniques; D006736:Horses; D013264:Stifle / Q000166:cytology* / Q000293:injuries*; D013582:Synovial Fluid / Q000166:cytology* / Q000502:physiology
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