Osteogenic gene array of osteoblasts cultured on a novel osteoinductive biphasic calcium phosphate bone grafting material.

OBJECTIVES: Recently, novel biphasic calcium phosphate (BCP) scaffolds have emerged as a new class of bone grafts with osteoinductive potential demonstrating the ability to form ectopic bone in extra-skeletal sites. The aim of the present study was to perform an osteogenic gene array to target possible genes responsible for eliciting the changes in cell expression responsible for inducing osteoblast differentiation. MATERIALS AND METHODS: Human MG63 osteoblast-like cells were seeded for 24 h on tissue culture plastic or osteoinductive BCP particles and analyzed for upregulated genes using an osteogenesis super-array. Osteoblast-related genes including those transcribed during bone mineralization, bone metabolism, cell growth and differentiation, as well as gene products representing extracellular matrix molecules, transcription factors, and cell adhesion molecules were investigated. RESULTS: An upregulation of genes transcribing biglycan (1.7-fold), bone morphogenetic proteins 1, 2, 4, 6, and 7 (1.5-2.1-fold), various collagen isoforms including 1a1, 1a2, 2a1, and 5a1 (1.73-2.72-fold), colony stimulating factor 2 (2.59-fold), fibroblast growth factor receptor 2 (1.79-fold), fibronectin (2.56-fold), integrin alpha 1, 2, and 3 (1.82-2.24-fold), SOX9 (2.75-fold), transforming growth factor beta receptor 2 (1.72-fold), vitamin D (1.89-fold), and vascular endothelial growth factor A and B (2.00, 1.75-fold) were all significantly (p < 0.05) increased on BCP particles when compared to control tissue culture plastic. CONCLUSION: In summary, a number of activated genes were involved in bone formation following osteoblast attachment to BCP particles. The involvement of key chondrogenic genes hints that bone grafts capable of spontaneously inducing ectopic bone formation may implicate endochondral ossification. Further investigations in the triggered pathways involved in the process of ectopic bone formation are necessary to understand the key inductive properties of these novel osteoinductive BCP particles. CLINICAL RELEVANCE: Novel osteoinductive BCP particles demonstrate a wide range of significant increases over several key molecules implicated in osteogenesis that may be implicated in their ability to form ectopic bone formation.

Gene array of PDL cells exposed to Osteogain in combination with a bone grafting material.

OBJECTIVES: The aim of the present study was to investigate the effects of Osteogain, a new formulation of enamel matrix derivative (EMD) in combination with a grafting material on a wide variety of genes for cytokines, transcription factors and extracellular matrix proteins involved in osteoblast differentiation. MATERIALS AND METHODS: Primary human periodontal ligament (PDL) cells were seeded on natural bone mineral (NBM) particles coated with Osteogain for 24 h and analyzed for regulated gene expression using a human osteogenesis gene super-array kit. Osteoblast-related genes include those transcribed during bone mineralization, ossification, bone metabolism, cell growth and differentiation as well as gene products representing extracellular matrix molecules, transcription factors and cell adhesion molecules. RESULTS: Osteogain significantly upregulated the expression of over 20 of the 100 genes examined including bone morphogenetic protein 2 (BMP2), TGFß1, fibroblast growth factor (FGF), epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) as well as some of their associated receptors. Osteogain also promoted gene expression of a number of osteoblast differentiation markers including collagen1α2 and alkaline phosphatase as well as cell adhesion molecules including fibronectin and a variety of integrin binding proteins. Interestingly, Osteogain promoted calcitonin receptor 55-fold and also promoted annexin A5 gene expression over 12-fold. CONCLUSION: The present study demonstrates that Osteogain is capable of either upregulating or downregulating the expression of a wide variety of genes including those for growth factors and cytokines when combined with a bone grafting material. CLINICAL RELEVANCE: The results from the present study demonstrate the large and potent effect of addition of Osteogain in combination to a bone grafting material over a wide variety of genes supporting osteogenesis.