BMP-7 regulates extracellular matrix profile and mineralization of cementoblasts

Objectives: Bone morphogenetic proteins (BMPs) play a critical role in the periodontal wound healing process by stimulating and regulating numerous activities including mitogenesis, chemotaxis, metabolism and differentiation of cells within the periodontium. The purpose of this study was to investigate the effects of BMP-7 which is known as potent bone inducing factor, on extracellular matrix (ECM) and adhesion molecules (AM) of cementoblasts using cDNA microarray analysis. Methods: Osteocalcin promoter driven SV40 transgenic mice were used to obtain immortalized cementoblasts. Cells were treated with DMEM containing 1) 5% FBS (Fetal Bovine Serum)+Ascorbic acid (AA, 50 ug/ml), 2) 5% FBS+ BMP-7 (50 ng/ml)+AA. Total RNAs were isolated from the cementoblasts at passage 16. After biotin-dUTP labeling of cDNA, hybridization was performed with pathway-specific gene expression profiling array membrane. ECM and AM mRNA expression values of cementoblasts treated with/without BMP-7 were analyzed. Values were compared using ScanAlyze and GEArray analyzer softwares. Von Kossa staining was also performed to determine mineralization of cementoblasts simultaneously. Results: Difference in ECM profile including integrins, matrix metalloproteinases (MMP) and tissue inhibitors of matrix metalloproteinases (TIMP) that are important in ECM regulation and mineralization, was noted between two groups. While at least 2 fold increase was noted in MMP-23,24 transcripts, decreased MMP-10,11 mRNA expressions were observed in the cells treated with BMP-7. Increased collagens (I and XVIII) and TIMP-1,2 transcripts were detected in the BMP-7 group. Furthermore, BMP-7 treatment increased cementoblast-mediated biomineralization in vitro when compared to untreated cells at day 8. Conclusion: Results of this study highlight the complex response of cementoblasts regarding ECM to specific factors like BMP-7. Continued research focused on investigating the genes/proteins regulating cell functions is vital toward obtaining information required to design clinical therapies (Supported by Scientific Research Coordination Center of Selcuk University, BAP/2002-190 and Turkish Scientific Research Council of Turkey SBAG/2648).