Effect of extracellular matrix protein on the rate of proteoglycan synthesis in rabbit intervertebral disc cells

Objective: The extracellular matrix (ECM) is very important for fundamental cellular processes. However, the effects of ECM proteins on intervertebral disc (IVD) cell proliferation and metabolism have not been clarified. To verify the effects of ECM proteins on DNA and proteoglycan (PG) synthesis of IVD cells, PG synthesis rate was measured in IVD cells cultured in monolayer with or without ECM protein. Methods: Nucleus pulposus (NP) cells and anulus fibrosus (AF) cells isolated from adolescent rabbits were cultured in monolayer with or without ECM protein and at different concentrations of ECM protein for 4-6 days. [S-35]Sulfate incorporation into PG in the cell-associated matrix (CM) formed around cells and the further-removed matrix (FRM) in labeling medium was measured and standardized to DNA content. Conclusions: NP cells in type I or type II collagen-coated plates significantly increased the rate of PG synthesis in both the CM and the FRM compared with those in uncoated plates and in fibronectin-coated plates; however, AF cells with ECM proteins did not increase the rate significantly. The rate of PG synthesis of nucleus cells was contra-dose dependent on both type I and type II collagen.