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Pigment epithelium derived factor—the product of the EPC-1 gene—is expressed by articular chondrocytes and up regulated in osteoarthritis
  1. D Pfander1,
  2. C Grimmer1,
  3. T Aigner2,
  4. B Swoboda1,
  5. R Schmidt3,
  6. T Cramer1,4
  1. 1Division of Orthopaedic Rheumatology, Department of Orthopaedic Surgery, University of Erlangen-Nuremberg, Erlangen, Germany
  2. 2Department of Pathology, University of Leipzig, Leipzig, Germany
  3. 3Department of Orthopaedic Surgery, University of Erlangen-Nuremberg, Erlangen, Germany
  4. 4Department of Hepatology and Gastroenterology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany
  1. Correspondence to:
    Dr D Pfander
    Division of Orthopaedic Rheumatology, Department of Orthopaedic Surgery im Waldkrankenhaus St Marien, University of Erlangen-Nuremberg, Rathsbergerstr 57, D-91054 Erlangen, Germany; Dpfander{at}t-online.de

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Proper function of a loadbearing joint depends on the structural integrity of articular cartilage, which can absorb and respond to mechanical stress.1 Increased synthesis of VEGF-A is assumed to be involved in cartilage neovascularisation in osteoarthritis (OA), thus contributing to cartilage damage during the course of OA.2,3

Previously, we and others have provided experimental evidence that VEGF-A synthesis by OA chondrocytes is controlled by the transcription factor hypoxia-inducible factor-1α.2–4 In contrast, pigment epithelium derived factor (PEDF) is one of the most potent natural inhibitors of angiogenesis and was recently described as being present in growth plate cartilage.5 PEDF constitutes a 50 kDa protein and is encoded by the EPC-1 gene.6,7 Based on our previous work, we aimed to determine whether PEDF is expressed in human normal and OA knee cartilage.

Twenty nine cartilage samples were obtained from patients during total knee replacement. In addition, nine human normal cartilage samples were obtained during necropsies. After fixation, specimens were embedded in paraffin wax, stained with safranin O, and were graded according to Mankin et al.8 For immunodetection of PEDF two different antibodies were used (polyclonal 1:100, Santa-Cruz Biotechnology Inc, …

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