157 the Thrombospondin-Related Protein, F-Spondin, Is Expressed in Embryonic Growth Plate Cartilage and Can Enhance the Expression of Chondrocyte Maturation Markers

F‐spondin, a neuroregulatory protein, is up‐regulated in osteoarthritis and regulates cartilage metabolism via TGF‐β activation

“…These observations suggest that F-spondin expression is associated with chondrocyte hypertrophy, a common feature of osteoarthritic cartilage in which articular chondrocytes appear to replicate the terminal differentiation process of embryonic growth plate chondrocytes during limb formation (11). Further evidence correlating F-spondin with chondrocyte hypertrophy has been observed in the embryonic growth plates of chick tibia, where F-spondin expression is confined only to hypertrophic and mineralized zones and demonstrates a similar expression profile to alkaline phosphatase (30). Despite these similarities, it is not clear whether F-spondin expression by OA chondrocytes reflects a reversion to an immature state or rather a dysregulated state that arises as a consequence of cell proliferation in an attempt to repair the damaged matrix.…”

“…These findings suggest that F-spondin expression in chondrocytes may be regulated by growth and differentiation factors. Indeed, preliminary observations from our group indicate that retinoic acid stimulates F-spondin expression during differentiation of embryonic growth plate chondrocytes (30); however, the significance of F-spondin induction in OA chondrocytes remains unclear. While a definitive role of FGF-2 in OA cartilage has not been established, elevated levels have been reported in synovial fluid of OA knees (31), and increased FGF-2 staining has been reported adjacent to cartilage lesions in early-stage OA (32).…”