Effect of Nanophase titanium on human osteoblast in vitro

Objective: To determine to effect of nanophase titanium on the attachment, proliferation, and differentiation of osteoblasts in vitro. Methods: Two groups of nanophase titanium were developed by ball milling with thickness of nanocrystallined layer of 45 nm (group A) and 24 nm (group B) respectively. Commercially pure titanium was used as control. The osteoblast-like cell line MG63 was seeded on3 groups. the MG63 cells were stained with TRITC-labeled phalloidin, and the morphological characteristics were observed. The cell proliferation was detected with MTT assay. The activity of alkaline phosphatase, and the production of Osteocalcin were determined by PNPP method, and Osteocalcin ELISA, respectively. The changes in the expression of Cbfa1 gene was measured by RT-PCR after 6 hours in culture. Results: MG63 cells grew well on 3 groups, cells in group A appeared more differentiated in shape and the margins of the cells were more irregular; at 24 hours, cell morphology in all groups became irregular and had no significant differences. Cell number increased from day 1 to day 7 on all discs. The cell proliferation was higher in group A than in groups B and control, but the difference was not significant. The ALP activity and OC production increased on all disc surface on days 1, 5, and 10 and decreased on day 15 (P<0.05), and on days 5 and 10, the ALP activity and OC production in group A was higher than that in other groups (P<0.05). The expression of cbfa1 were up-regulated (P<0.05) in group A. Conclusion: Nanophase titanium developed by ball milling is a promising material that significantly improved the attachment, function (ALP and OC),and gene expression of osteoblast. Further in-depth investigation is necessary.