title: Characterization of cells from pannus-like tissue over articular cartilage of advanced osteoarthritis.
abstract: OBJECTIVE
  To identify the characteristics of cells isolated from pannus-like soft tissue on osteoarthritic cartilage (OA pannus cells), and to evaluate the role of this tissue in osteoarthritis (OA).
  
  
  METHODS
  OA pannus cells were isolated from pannus-like tissues in five joints obtained during arthroplasty. The phenotypic features of the isolated cells were characterized by safranin-O staining and immunohistochemical studies. Expression of MMP-1, MMP-3 and MMP-13 was also assessed using reverse transcriptase-polymerase chain reactions (RT-PCR), enzyme-linked immunosorbent assay (ELISA) and immunocytochemistry.
  
  
  RESULTS
  Foci and plaque formation of pannus-like tissue over cartilage surface were found in 15 of 21 (71.4%) OA joints macroscopically, and among them, only five samples had enough tissue to be isolated. OA pannus cells were positive for type I collagen and vimentin, besides they also expressed type II collagen and aggrecan mRNA. Spontaneous expression of MMP-1, MMP-3 and MMP-13 was detected in OA pannus cells. Similar or higher levels of MMPs were detected in the supernatant of cultured OA pannus cells compared to OA chondrocytes, and among these MMP-3 levels were relatively higher in OA pannus cells. Immunohistochemically, MMP-3 positive cells located preferentially in pannus-like tissue on the border of original hyaline cartilage.
  
  
  CONCLUSIONS
  Our results showed that OA pannus cells shared the property of mesenchymal cells and chondrocytes; however, their origin seemed different from chondrocytes or synoviocytes. The spontaneous expression of MMPs suggests that they are involved in the articular degradation in OA.
authors.affiliation: Department of Bioregulation, Institute of Medical Science, St. Marianna University, Kawasaki 216-8512, Japan.
authors.forename: G-H
authors.initials: GH
authors.lastname: Yuan
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Masuko-Hongo
authors.forename: A
authors.initials: A
authors.lastname: Shibakawa
authors.forename: T
authors.initials: T
authors.lastname: Kato
authors.forename: K
authors.initials: K
authors.lastname: Nishioka
authors.forename: H
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000378:metabolism / Q000473:pathology*; D002478:Cells, Cultured; D003094:Collagen / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D020782:Matrix Metalloproteinases / Q000032:analysis*; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology*; D015207:Osteoarthritis, Hip / Q000378:metabolism / Q000473:pathology; D020370:Osteoarthritis, Knee / Q000378:metabolism / Q000473:pathology; D011509:Proteoglycans / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014746:Vimentin / Q000032:analysis
chemical_list: D011509:Proteoglycans; D014746:Vimentin; D003094:Collagen; D020782:Matrix Metalloproteinases