BMP-7 regulates mineralization of Periodontal Ligament Cells

Objectives: The periodontal ligament (PDL) has been shown to possess the ability to regenerate both new cementum and alveolar bone. Bone Morphogenetic Protein (BMP)-7 plays an important role in regulating osteoblast differentiation and subsequent bone formation. The objective of this study was to determine the effects of BMP-7 on PDL cell behavior including the ability to alter genes associated with extracellular matrix formation, in vitro.

Methods: PDL cells were obtained from premolar teeth that were extracted for orthodontic reasons. Cells were exposed to different BMP-7 concentrations (25, 50 and 100ng/ml) to asses cell survival using MTT assay at 24 and 72 hours. PDL cells were treated with factors as follows; 1) %5 FBS 2) %5 FBS+MM [MM= ascorbic acid (AA, 50 μg/ml) and β-glycerophosphate (BGP, 10 mM)] 3) %5 FBS+ BMP-7 (25 ng/ml)+MM 4) %5 FBS+ BMP-7 (50 ng/ml)+MM 5) %5 FBS+BMP-7 (100 ng/ml)+MM in DMEM for mineralization experiments. Biomineralization of PDL cells was examined with von Kossa assay on day 24. Total-RNA was isolated from PDL cells on days 8 and 12 and mRNA expressions of PDL cells treated with different concentration of BMP were evaluated for mineralized tissue markers including type I Collagen (COL I), Bone Sialoprotein (BSP), Osteocalcin (OCN) and Osteopontin (OPN) using semiquantitative RT-PCR.

Results: While there was no apparent difference in COL I mRNA expression, BMP-7 treatments induced BSP and OPN mRNA expression. OCN mRNA expression was also up-regulated except for 100 ng/ml BMP7 treated cells. BMP-7 increased mineral nodule formation of PDL cells with the dose dependent manner.

Conclusion: The results of this study revealed that BMP-7 may be a good candidate to induce PDL cells differentiating to cementoblasts and/or osteoblasts to obtain periodontal regeneration (This study was supported by Selcuk University Research Foundation/BAP).