Vascular endothelial growth factor (VEGF) is expressed during articular cartilage growth and re-expressed in osteoarthritis

Abstract

Introduction: Vascular endothelial growth factor (VEGF) is expressed in osteoarthritic articular cartilage. However, the pattern of VEGF expression throughout the whole life cycle of articular cartilage is not well elucidated. The aim of the study was to investigate the spatiotemporal expression of VEGF and its receptors, vascular endothelial growth factor receptor-1 (VEGFR1) and vascular endothelial growth factor receptor-2 (VEGFR2), in articular cartilage during growth, maturation and degeneration, using the guinea pig model of spontaneous osteoarthritis. Materials and Methods: Sections of tibial plateaus aged 2, 6 and 12 months were obtained, representing growing, mature and osteoarthritic cartilage respectively. Expression ofVEGF and its receptors was determined by immunohistochemistry and in situ hybridisation. Results: At 2 months, VEGF and its receptors were expressed in chondrocytes within the superficial layer of the articular cartilage. At 6 months, no expression of VEGF and its receptors was noted. In the 12-month-old specimens, VEGF and its receptors were expressed in chondrocytes within articular cartilage that exhibited osteoarthritic changes (medial tibial plateaus), but not in the histologically normal lateral plateaus. Conclusion: This spatiotemporal distribution of VEGF and its receptors suggests that VEGF is expressed during articular cartilage growth, becomes quiescent at maturity, and is re-expressed in osteoarthritis.