Growth factor expression following clinical mandibular distraction osteogenesis in humans and its comparison with existing animal studies

Abstract

Lengthening the mandible by distraction osteogenesis (DO) is nowadays a well recognized technique in maxillofacial surgery. In this study growth factor expression profiles were examined in biopsies taken from six patients undergoing mandibular DO and compared with findings from a sheep model for mandibular DO. In all patients (and sheep), the ascending ramus was distracted 10-15 mm at a rate of 1mm/day using an intraoral device. Biopsies were taken from the centre of the distraction zone 21 days after completion of distraction. Using standard immunohistochemical techniques, samples were stained for platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), basic fibroblast growth factor (bFGF) and bone morphogenetic proteins-2, -4 and -7 (BMP-2, -4, -7), matrix metalloproteinases-1 and -3 (MMP-1, -3), the vascular endothelial growth factor (VEGF), a marker for endothelial cells (CD-31) and type IV collagen (Col IV). Positive staining for PDGF, bFGF, TGF-beta, BMP-2, -4, and -7 was noted in cells and matrix components. There was intense staining for MMP-1. Strong staining for CD-31 and COL IV was observed adjacent to vessels. VEGF staining was less specific. Similar findings were noted in the sheep model. Growth factor expression in the human distraction site is similar to that in the sheep model.