Matrix metalloproteinases MMP-2, -9 and tissue inhibitors TIMP-1, -2 expression and secretion by primary human osteoblast cells in response to titanium, zirconia, and alumina ceramics

Osteogenic properties of bone cells are a key parameter governing osseointegration of implant devices. In this context, osteoblasts have a central role via extracellular matrix synthesis and remodeling that they regulate through different protease activity. In this study, we have analyzed the expression of two matrix metalloproteinases (MMPs): MMP‐2 (72 kDa) and MMP‐9 (92 kDa) and their specific tissue inhibitors TIMP‐1 and TIMP‐2 in primary human osteoblastic cells. The effect of titanium, zirconia, and alumina ceramics on the synthesis of these proteases was assessed using reverse transcriptase‐polymerase chain reaction, enzyme‐linked immunosorbent assay, and zymographic analysis. Our results showed that osteoblasts express MMP‐2 and ‐9 mRNA. Furthermore, MMP‐2 mRNA expression was decreased by titanium and increased by alumina whereas zirconia did not have any significant effect. Conversely, MMP‐9 mRNA expression was stimulated by titanium but decreased with zirconia, whereas alumina induced no significant changes. Zymographic analysis has evidenced pro‐MMP‐2 gelatinolytic activity in all cell populations with time‐dependent increase profile; pro‐MMP‐9, however, was not detected. Enzyme‐linked immunosorbent assay data confirmed the production of MMP‐2 and very low levels of MMP‐9. In addition, TIMP‐1 was secreted in 24‐h‐cultured cells and increased to maximal level at 48–72 h whereas TIMP‐2 levels were very low. The interactions between human osteoblasts and the studied biomaterials altered both MMP‐2, ‐9 and TIMP‐1expression indicating that biomaterials may influence osseointegration and bone remodeling. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 114–122, 2004