title: Pleiotrophin, an embryonic differentiation and growth factor, is expressed in osteoarthritis.
abstract: OBJECTIVE
  Pleiotrophin (PTN) is a 15.3 kDa heparin-binding peptide, which is expressed in mesodermal and neuroectodermal cells during development, but rarely in adult tissues. In fetal or juvenile cartilage, PTN is an abundant protein and appears to be involved in chondrocyte differentiation. Since developmentally regulated factors often re-appear in the disease state, we examined PTN expression in cartilage and synovial fluid of patients with osteoarthritis (OA).
  
  
  METHODS
  PTN mRNA and protein expression was assayed by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot, the protein was localized by immunohistochemistry and quantified by enzyme-linked immunoassay (ELISA).
  
  
  RESULTS
  PTN was undetectable in normal adult cartilage, but PTN mRNA and protein were found in OA. In cartilage from the tibial plateaus of OA patients, PTN could be immunostained in clusters of superficial chondrocytes. In the synovial fluids of OA patients, PTN concentrations were elevated in earlier OA stages, but rarely in late OA stages. Chondrosarcomas were PTN-immunonegative.
  
  
  CONCLUSIONS
  In addition to certain types of cancer, the embryonic growth and differentiation factor PTN is found also in adults in inflammatory diseases. In OA, PTN is especially expressed in early stages, and PTN concentrations in the synovial fluid could serve as a marker for the progress of the disease. PTN might be involved in cartilage repair in OA, in particular, in earlier stages.
authors.affiliation: Department of Anatomy, University of Kiel, D-24098, Kiel, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Pufe
authors.forename: M
authors.initials: M
authors.lastname: Bartscher
authors.forename: W
authors.initials: W
authors.lastname: Petersen
authors.forename: B
authors.initials: B
authors.lastname: Tillmann
authors.forename: R
authors.initials: R
authors.lastname: Mentlein
mesh_terms: D000328:Adult; D000368:Aged; D015153:Blotting, Western / Q000379:methods; D002352:Carrier Proteins / Q000032:analysis*; D002358:Cartilage, Articular / Q000378:metabolism; D002454:Cell Differentiation; D019902:Chondrocytes / Q000378:metabolism; D016207:Cytokines / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006133:Growth Substances / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008934:Mitogens / Q000032:analysis*; D010003:Osteoarthritis / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013582:Synovial Fluid / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; D006133:Growth Substances; D008934:Mitogens; D012333:RNA, Messenger; C066845:pleiotrophin