A case of mandible hypoplasia treated with autologous bone graft from mandibular symphysis: expression of VEGF and receptors in bone regeneration.

The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) system plays an important role inangiogenesis and osteogenesis during both skeletal development and postnatal bone growth and repair.Indeed, protein expression changes of this system could contribute to craniofacial defects commonlyassociated with a variety of congenital syndromes. Similarly to other craniofacial bones, mandible arisesfrom neural crest cells of the neuroectodermal germ layer, and undergoes membranous ossification.Here, we report a case of left mandibular hypoplasia in a 42-year-old man treated with autologous bonegraft from mandibular symphysis. After 3 months from surgical reconstruction, the protein expressionof VEGF and receptors (VEGFR-1, -2 and -3) in regenerated bone tissue was evaluated by immunohisto-chemistry. At variance with the mandibular symphysis bone harvested for graft surgery, we observed denovo expression of VEGF and VEGFRs in osteoblasts and osteocytes from post-graft regenerating mandiblebone tissue. In particular, while VEGFR-1 and VEGFR-3 immunopositivity was widespread in osteoblasts,that of VEGFR-2 was scattered. Among the three receptors, VEGFR-3 was the more intensively expressedboth in osteoblasts and osteocytes. These findings suggest that VEGFR-2 might be produced during theearly period of regeneration, while VEGFR-1 might participate in bone cell maintenance during the mid-dle or late consolidation period. VEGFR-3 might, instead, represent a specific signal for ectomesenchymallineage differentiation during bone regeneration. Modulation of VEGF/VEGFR signaling could contributeto graft integration and new bone formation during mandibular regeneration.