title: Enhancing and maintaining chondrogenesis of synovial fibroblasts by cartilage extracellular matrix protein matrilins.
abstract: OBJECTIVE
  Cartilage-specific extracellular matrix (ECM) proteins have been proposed to play key roles in modulating cellular phenotypes during chondrogenesis of mesenchymal stem cells. Matrilin (MATN)1 and MATN3 are among the most up-regulated ECM proteins during chondrogenesis. The aim of this study was to analyze their roles in chondrogenesis of mesenchymal fibroblasts from synovium.
  
  
  METHODS
  Primary synovial fibroblasts (SFBs) were purified from porcine synovium and incubated in pellet culture for 18 days. Chondrogenesis of SFB was analyzed by histological staining with safranin-O/fast green, and by quantifying glycosaminoglycans (GAG) with dimethylmethylene blue assay. The mRNA levels of chondrogenic markers including collagen II, aggrecan, and Sox 9 were quantified by real-time reverse transcription polymerase chain reaction, while the protein levels of Col II and MATNs were determined by western blot analysis.
  
  
  RESULTS
  SFBs underwent chondrogenesis after incubation with transforming growth factor-beta1 (TGF-beta1) for 3 days; however, this process was attenuated during the subsequent incubation period. Expression of a Matn1 or Matn3 cDNA maintained and further enhanced chondrogenesis of SFBs as shown by increased cartilaginous matrix areas, elevated amount of GAG, and stimulated expression of chondrogenic markers.
  
  
  CONCLUSIONS
  Our findings suggest a novel function for MATN1 and MATN3 to maintain and enhance chondrogenesis of mesenchymal fibroblasts initiated by TGF-beta. Our results also support a critical role of cartilage-specific ECM proteins to modulate cellular phenotypes in the microenvironment during chondrogenic differentiation.
authors.affiliation: Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, Morgantown, WV 26506, USA.
authors.forename: M
authors.initials: M
authors.lastname: Pei
authors.forename: J
authors.initials: J
authors.lastname: Luo
authors.forename: Q
authors.initials: Q
authors.lastname: Chen
mesh_terms: D000818:Animals; D002356:Cartilage / Q000378:metabolism* / Q000503:physiopathology; D064236:Cartilage Oligomeric Matrix Protein; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D020219:Chondrogenesis / Q000235:genetics / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D064235:Matrilin Proteins; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D013583:Synovial Membrane / Q000378:metabolism; D023822:Tissue Engineering / Q000379:methods / Q000639:trends; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism
chemical_list: D064236:Cartilage Oligomeric Matrix Protein; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C577539:MATN1 protein, human; D064235:Matrilin Proteins; C577553:TSP5 protein, human; D016212:Transforming Growth Factor beta