[Effect of titanium particles on proliferation, differentiation, and cytomorphology of osteoblasts]

To study the effect of titanium particles on the proliferation, differentiation, and cytomorphology of osteoblasts, and to explore the possible internal relations and mechanism.

Calvarial osteoblasts were separated from 10 newborn Sprague Dawley rats by repeated enzyme digestion, and were cultured in vitro. The cells were identified by alkaline phosphatase (ALP) staining and alizarin red staining. The cells at passage 3 were cultured with titanium particles culture medium at concentrations of 0.01, 0.05, 0.1, 0.5, and 1 mg/mL (0.01, 0.05, 0.1, 0.5, and 1 mg/mL groups). The absorbance (A) values were detected by cell counting kit 8 at 7 days after cultured to compare the effect of titanium particles at different concentrations on proliferation, and median lethal concentration was screened out. The expression of collagen type I was detected by ELISA to observe the effect of titanium particles on differentiation. The osteoblasts co-cultured with titanium particles of median lethal concentration (experimental group) for 7 days, and double fluorescence staining with FITC-phalloidine and propidium iodide was performed. The cytomorphology variation of osteoblasts after swallowing titanium particles was observed under laser scanning confocal microscope. The osteoblasts at passage 3 cultured with culture medium without titanium particles served as control group.

The cultured cells were identified as osteoblasts by ALP staining and alizarin red staining. Different concentrations of titanium particles could inhibit osteoblasts proliferation and differentiation in varying degrees, showing significant difference when compared with the control group at 7 days after culture (P < 0.05). The cell proliferation and differentiation were decreased with increased titanium particles concentration; significant differences were found between the other groups (P < 0.05) except 0.01 and 0.05 mg/mL groups (P > 0.05). The median lethal concentration of titanium particles was 0.5 mg/mL. Laser scanning confocal microscope showed cellular shrinking, microfilaments distortion, pseudopodia contraction of osteoblasts that swallowed titanium particles in the experimental group.

Titanium particles can inhibit proliferation and differentiation of osteoblasts. The effect may be related to variation of cytomorphology after swallowing titanium particles.