Application of nerve growth factor by gel increases formation of bone in mandibular distraction osteogenesis in rabbits

The long period of bony consolidation is a concern in mandibular distraction osteogenesis (DO). We have previously shown that repeated local injections of human nerve growth factor beta (NGF beta) can appreciably improve bony consolidation in a rabbit model of DO. The present study was designed to test the effect of a single injection of human NGF beta delivered by collagen/nano-hydroxyapatite/kappa-carrageenan gels to sites of new bony formation in DO. Rabbits underwent mandibular DO at a rate of 0.75 mm/12 h for 6 clays. At the end of the distraction period, the following injections were given percutaneously into the callus (n = 6 in each of the four groups): human NGF beta in the gel; human NGF beta in saline; the gels alone; and saline alone. Fourteen days after the end of distraction, mechanical testing, histological and histomorphometric variables of the new bone were evaluated. Histologically, the NGF beta group had more advanced consolidation than the other three groups. Both maximal load and bone volume/total volume in this group were significantly higher than in the other three (P < 0.05). In conclusion, the delivery of human NGF beta in the gels results in better acceleration of new bone formation than when it is given in saline, and may be a possible way to shorten the duration of craniofacial DO. (C) 2010 Published by Elsevier Ltd on behalf of The British Association of Oral and Maxillofacial Surgeons.