The role of insulin-like growth factor-I in hyaluronan mediated repair of cultured cartilage explants

Objective and Design:To test whether hyaluronan (HA) restores proteoglycan (PG) in fibronectin fragment (Fn-f) damaged cartilage through activities of insulin-like growth factor 1 (IGF-1). Material:Bovine cartilage explants were studied. Methods:Cartilage PG content was measured by a dye binding assay. PG synthesis was measured by incorporation of radiolabeled sulfate. Release of IGF-1 from explants was measured by ELISA. Results:Higher mass HA forms were more reparative than smaller and enhanced PG synthesis in explants, but not in monolayer cultures. Higher mass HA enhanced PG synthesis and retention of IGF-1 within the explants while IGF-1 binding proteins decreased activities of HA. Conclusions:The reparative effects of HA appear to involve enhanced PG synthesis through IGF-1 and requires cartilage matrix.