Fig. 6

Effects of Ti particle-induced changes in MLO-Y4 cells on ALP activity and staining of MC3T3-E1 cells in two co-culture models on day 7. Data showing ALP activity are expressed as mean ± S.D. a In the “Cell Contact” model, ALP activity of MC3T3-E1 cells significantly decreased as the concentration of Ti particles increased (*p < 0.05, **p < 0.01). b In the “No Cell Contact” model, the ALP activity of MC3T3-E1 cells treated with 0.1 mg/mL and 1.0 mg/mL Ti particles did not differ significantly from the control. c ALP staining in the “Cell Contact” model showed fewer positive cells (cytosol red coloration) in the 0.1 mg/mL and 1.0 mg/mL groups compared with the control. In the “No Cell Contact” model, no significant differences in ALP staining were observed in any group