BACKGROUND AND OBJECTIVE

A number of bone-filling materials containing calcium (Ca(2+) ) and phosphate (P) ions have been used in the repair of periodontal bone defects; however, the effects that local release of Ca(2+) and P ions has on biological reactions are not fully understood. In this study, we investigated the effects of various levels of Ca(2+) and P ions on the proliferation, osteogenic differentiation and mineralization of human periodontal ligament cells (hPDLCs).

MATERIAL AND METHODS

The hPDLCs were obtained using an explant culture method. Defined concentrations and ratios of ionic Ca(2+) to inorganic P were added to standard culture and osteogenic induction media. The ability of hPDLCs to proliferate in these growth media was assayed using the Cell Counting Kit-8. Cell apoptosis was evaluated by the fluorescein isothiocyanate-annexin V/propidium iodide double-staining method. Osteogenic differentiation and mineralization were investigated by morphological observations, alkaline phosphatase activity and Alizarin Red S/von Kossa staining. The mRNA expression of osteogenic related markers was analysed using RT-PCR.

RESULTS

Within the ranges of Ca(2+) and P ion concentrations tested, we observed that increased concentrations of Ca(2+) and P ions enhanced cell proliferation and formation of mineralized matrix nodules, whereas alkaline phosphatase activity was reduced. The RT-PCR results showed that elevated concentrations of Ca(2+) and P ions led to a general increase of Runx2 mRNA expression and decreased alkaline phosphatase mRNA expression, but gave no clear trend on osteocalcin mRNA levels.

CONCLUSION

The concentrations and ratios of Ca(2+) and P ions could significantly influence proliferation, differentiation and mineralization of hPDLCs. Within the range of concentrations tested, we found that the combination of 9.0 mm Ca(2+) ions and 4.5 mm P ions were the optimal concentrations for proliferation, differentiation and mineralization in hPDLCs.