BMP-2 and bFGF in an irradiated bone model

Introduction: Basic fibroblast growth factor (bFGF) is considered to enhance angiogenesis and to support bone formation in the presence of vital bone cells. Bone morphogenetic protein-2 (rhBMP-2) is known to induce bone formation. The aim of this study was to analyze the effect of bFGF and rhBMP-2 in the irradiated mandible. Material and methods: The right mandibles of 24 rats were irradiated with a single dose of 20 Gy at a high-dose-rate (HDR) after loading machine (bio effective equivalent dose to ca. 45 X 2 Gy). After 12 weeks 100 mu g rhBMP-2 (n = 6 animals, group 1), 100 mu g bFGF (n = 6 animals, group 2) and 100 mu g rhBMP-2 plus 100 mu g bFGF (n = 6 animals, group 3) were injected along the right mandible (left mandible: no irradiation, no growth factor). Another 6 animals (group 4) remained untreated after the irradiation. After another 7 weeks the specimens were examined by non-decalcified histology. Results: Bone apposition of the experimental versus control sides was not statistically significantly different when one of the growth factors was applied alone (rhBMP-2:p = 0.917; bFGF:p = 0.345). Average bone apposition was significantly decreased on the experimental sides of group 3 (rhBMP-2 + bFGF: p = 0.046) and group 4 (p = 0.008). Average bone densities were unaffected in all settings (for all p > 0.1). Conclusions: The application of bFGF and the application of rhBMP-2 alone did result in predictable bone generation in the irradiated mandible with the bone apposition being equal to that of the non-irradiated side. The application of both growth factors together or none at all after irradiation results in significantly reduced bone apposition. (C) 2007 European Association for Cranio-Maxillofacial Surgery.