Osteostatin improves the osteogenic activity of fibroblast growth factor-2 immobilized in Si-doped hydroxyapatite in osteoblastic cells

• Published in: Acta biomaterialia 2012-07, Vol.8 (7), p.2770-2777
• Main Authors: Lozano, Daniel, Feito, María José, Portal-Núñez, Sergio, Lozano, Rosa María, Matesanz, María Concepción, Serrano, María Concepción, Vallet-Regí, María, Portolés, María Teresa, Esbrit, Pedro
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Alkaline Phosphatase - metabolism; Animals; Antibodies, Neutralizing - pharmacology; Biocompatible Materials - pharmacology; Calcification, Physiologic - drug effects; Cell Line; Cell Proliferation - drug effects; Culture Media, Conditioned - pharmacology; Durapatite - pharmacology; Fibroblast Growth Factor 2 - pharmacology; Fibroblast growth factor-2; Gene Expression Regulation - drug effects; Humans; Immobilized Proteins - pharmacology; Mice; Osteoblastic function; Osteoblasts - drug effects; Osteoblasts - enzymology; Osteoblasts - metabolism; Osteogenesis - drug effects; Osteostatin; Parathyroid hormone-related protein; Parathyroid Hormone-Related Protein - pharmacology; Peptide Fragments - pharmacology; Si-based hydroxyapatite; Sus scrofa; Vascular Endothelial Growth Factor A - genetics; Vascular Endothelial Growth Factor A - metabolism; Vascular Endothelial Growth Factor Receptor-1 - genetics; Vascular Endothelial Growth Factor Receptor-1 - metabolism; Vascular Endothelial Growth Factor Receptor-2 - genetics; Vascular Endothelial Growth Factor Receptor-2 - metabolism
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2012.04.002

Si-doped hydroxyapatite (Si-HA) is a suitable ceramic for the controlled release of agents to improve bone repair. We recently showed that parathyroid hormone-related protein (PTHrP) (107–111) (osteostatin) has remarkable osteogenic features in various in vitro and in vivo systems. Fibroblast growth factor (FGF)-2 modulates osteoblastic function and induces angiogenesis, and can promote osteoblast adhesion and proliferation after immobilization on Si-HA. In the present study we examined whether osteostatin might improve the biological efficacy of FGF-2-coated Si-HA in osteoblastic MC3T3-E1 cells in vitro. We found that Si-HA/FGF-2 in the presence or absence of osteostatin (100nM) similarly increased cell growth (by about 50%). However, addition of the latter peptide to Si-HA/FGF-2 significantly enhanced gene expression of Runx2, osteocalcin, vascular endothelial growth factor (VEGF) and the VEGF receptors 1 and 2, without significantly affecting that of FGF receptors in these cells. Moreover, secreted VEGF in the MC3T3-E1 cell conditioned medium, which induced the proliferation of pig endothelial-like cells, was also enhanced by these combined factors. The synergistic action of osteostatin and Si-HA/FGF-2 on the VEGF system was abrogated by a mitogen-activated protein kinase inhibitor (U0126) and by the calcium antagonist verapamil. This action was related to an enhancement of alkaline phosphatase activity and matrix mineralization in MC3T3-E1 cells, and also in primary human osteoblastic cells. These in vitro data show that osteostatin increases the osteogenic efficacy of a Si-HA/FGF-2 biomaterial by a mechanism involving mitogen-activated protein kinases and intracellular Ca2+. These findings provide an attractive strategy for bone tissue engineering.