title: Regeneration of defects in articular cartilage in rat knee joints by CCN2 (connective tissue growth factor).
abstract: CTGF/CCN2, a hypertrophic chondrocyte-specific gene product, possessed the ability to repair damaged articular cartilage in two animal models, which were experimental osteoarthritis and full-thickness defects of articular cartilage. These findings suggest that CTGF/CCN2 may be useful in regeneration of articular cartilage.
  
  
  BACKGROUND
  Connective tissue growth factor (CTGF)/CCN2 is a unique growth factor that stimulates the proliferation and differentiation, but not hypertrophy, of articular chondrocytes in vitro. The objective of this study was to investigate the therapeutic use of CTGF/CCN2.
  
  
  METHODS
  The effects of recombinant CTGF/CCN2 (rCTGF/CCN2) on repair of damaged cartilage were evaluated by using both the monoiodoacetic acid (MIA)-induced experimental rat osteoarthritis (OA) model and full-thickness defects of rat articular cartilage in vivo.
  
  
  RESULTS
  In the MIA-induced OA model, quantitative real-time RT-PCR assays showed a significant increase in the level of CTGF/CCN2 mRNA, and immunohistochemical analysis and in situ hybridization revealed that the clustered chondrocytes, in which clustering indicates an attempt to repair the damaged cartilage, produced CTGF/CCN2. Therefore, CTGF/CCN2 was suspected to play critical roles in cartilage repair. In fact, a single injection of rCTGF/CCN2 incorporated in gelatin hydrogel (rCTGF/CCN2-hydrogel) into the joint cavity of MIA-induced OA model rats repaired their articular cartilage to the extent that it became histologically similar to normal articular cartilage. Next, to examine the effect of rCTGF/CCN2 on the repair of articular cartilage, we created defects (2 mm in diameter) on the surface of articular cartilage in situ and implanted rCTGF/CCN2-hydrogel or PBS-hydrogel therein with collagen sponge. In the group implanted with rCTGF/CCN2-hydrogel collagen, new cartilage filled the defect 4 weeks postoperatively. In contrast, only soft tissue repair occurred when the PBS-hydrogel collagen was implanted. Consistent with these in vivo effects, rCTGF/CCN2 enhanced type II collagen and aggrecan mRNA expression in mouse bone marrow-derived stromal cells and induced chondrogenesis in vitro.
  
  
  CONCLUSIONS
  These findings suggest the utility of CTGF/CCN2 in the regeneration of articular cartilage.
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishida
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kubota
authors.forename: Shunji
authors.initials: S
authors.lastname: Kojima
authors.forename: Takuo
authors.initials: T
authors.lastname: Kuboki
authors.forename: Kyouji
authors.initials: K
authors.lastname: Nakao
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kushibiki
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tabata
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takigawa
mesh_terms: D053674:Aggrecans; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D001861:Bone Regeneration / Q000187:drug effects*; D002358:Cartilage, Articular / Q000187:drug effects* / Q000293:injuries / Q000503:physiopathology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D020219:Chondrogenesis / Q000187:drug effects; D024121:Collagen Type X / Q000235:genetics; D055513:Connective Tissue Growth Factor; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D016326:Extracellular Matrix Proteins / Q000235:genetics; D015870:Gene Expression / Q000235:genetics; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D019807:Iodoacetic Acid / Q000494:pharmacology; D007718:Knee Injuries / Q000188:drug therapy / Q000503:physiopathology; D037181:Lectins, C-Type; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D020370:Osteoarthritis, Knee / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D011509:Proteoglycans / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000187:drug effects / Q000378:metabolism; D019063:Tenascin / Q000235:genetics
chemical_list: C508320:Acan protein, mouse; C508321:Acan protein, rat; D053674:Aggrecans; C526318:CCN2 protein, mouse; C526316:CCN2 protein, rat; D024121:Collagen Type X; D016326:Extracellular Matrix Proteins; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D037181:Lectins, C-Type; D011509:Proteoglycans; D011994:Recombinant Proteins; D019063:Tenascin; D055513:Connective Tissue Growth Factor; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D019807:Iodoacetic Acid