Synthetic ameloblastin peptide stimulates differentiation of human periodontal ligament cells

Objective: This study investigates the effect of the N-terminal region of a synthetic porcine ameloblastin peptide on the proliferation and differentiation of human periodontal ligament cells (PDLC). Design: We used a cell counter to assess the effect of ameloblastin peptides on the proliferation of PDLC. To investigate the effect of ameloblastin peptides on the differentiation of PDLC, we examined quantitative analysis of alkaline phosphatase (ALP) activity by the Bessey-Lowry enzymological method, mineral nodule formation by Dahl's method, and expression of mineralization-related genes by RT-PCR. We used an anti-ameloblastin antibody to determine whether stimulation of ALP activity was caused by the peptide. Results: At all concentrations examined, the effect of the ameloblastin peptide on cell proliferation was not significantly different compared with the control. However, the peptide significantly stimulated ALP activity in a dose-dependent manner. ALP activity was significantly inhibited by an anti-ameloblastin antibody, which caused ALP levels to revert to their approximate levels in the untreated condition. At concentrations greater than 1 ng/ml, the peptide promoted mineralized nodule formation of PDLC. And the peptide induced higher expressions of ALP and bone sialoprotein (BSP) than the control. Conclusion: Our results show that the ameloblastin peptide upregulate ALP and BSP levels and can enhance calcification of PDLC. Thus, we suggest that the N-terminal synthetic ameloblastin peptide promotes the differentiation activity of PDLC.