[Role of extracellular signal-regulated kinase in osteoblast differentiation on roughened titanium surfaces]

Abstract

Purpose: The purpose of this study was to evaluate the effect of sand-blasted and acid-etched titanium surface on MC3T3-E1 murine pre-osteoblast cell differentiation, and investigate the pathway of regulating osteogenic differentiation of MC3T3-E1 cells on sand-blasted and acid-etched titanium surface in order to elucidate the regulatory mechanisms of surface roughness on osteoblastic differentiation.

Methods: The characteristic of PT polished titanium (PT), sand-blasted and acid-etched (SLA) titanium surface were examined by scanning electron microscopy (SEM). Real-time PCR was applied to detect the expression of osteogenic genes including Runx2, OSX, OCN and OPN of the MC3T3-E1 cells cultured on the 2 groups of substrates.ERK1/2 activities in MC3T3-T1 cells were measured by Western blot on SLA surface. The data was analyzed using SAS9.0 software package.

Results: The result of SEM observation showed that the PT surface was turned titanium surfaces with the mean peak to valley roughness (Ra) of 0.2 μm and the corresponding Ra value of SLA was 3.2 μm. The expression levels of Runx2, OSX, OPN and OCN were significantly higher and the cell proliferation was significantly lower on SLA surfaces than on PT surfaces (P<0.05). The expression levels of Runx2, OSX, OPN and OCN were up-regulated by the effect of SLA surface with PD98095. Compared with PT surface, ERK1/2 phosphorylation was continuously inhibited by SLA. Moreover, PT surfaces treated with PD98095 and SLA surfaces without PD98095 both demonstrated reduced ERK1/2 phosphorylation of the cells and the inhibitive effect of SLA surfaces was milder than that of PD98095.

Conclusions: Surface roughness is an important factor that determines osteoblast behaviors. Surface roughness of titanium substrates seems to enhance the osteoblastic differentiation of MC3T3-E1 cells and the enhancing effect of surface roughness on cell differentiation may be mediated by suppressing the activity of ERK1/2 pathway.