Expression of Vasculoendothelial Growth Factor in Distraction Osteogenesis of Rat Tibia / 대한정형외과연구학회지

PURPOSE: In order to delineate its function in distraction osteogenesis, the temporal and spatial expression patterns of vasculoendothelial growth factor(VEGF) mRNA and protein were investigated. MATERIALS AND METHODS: Distraction osteogenesis was carried out in the tibiae of Sprague-Dawley rat using bilateral monofixators. Total RNA was prepared from the bone tissue including distraction gap at postoperative 1, 2, 3, 4 weeks and in unoperative one. The temporal pattern of mRNA expression was observed using reverse transcription - polymerase chain reaction. Spatial expression of mRNA and protein of VEGF were observed using in-situ hybridization and immunohistochemistry. RESULTS: VEGF mRNA was expressed throughout the whole procedure, and the relative dominance of splicing variants was changing during distraction osteogenesis. VEGF expression of both mRNA and protein was highest in the immature osteoblasts at the primary matrix front. CONCLUSION: These data suggest that VEGF plays an important role in distraction osteogenesis, not only of angiogenesis but also of osteoblastic differentiation.

Molecular Characterization of Congenital Pseudoarthrosis of the Tibia Associated with Neurofibromatosis / 대한정형외과학회잡지

PURPOSE: Congenital pseudarthrosis of the tibia, which is recalcitrant to treatments and prone to recur, is frequently associated with neurofibromatosis. The causative gene for neurofibromatosis, NF1, has been identified, but the pathomechanism of congenital pseudarthrosis has not been elucidated. The purposes of this study were to establish primary cell culture from the fibrous hamartoma tissue of pseudoarthrosis, and to compare the gene expression patterns of the fibrous hamartoma and normal bone. MATERIALS AND METHODS: Incubation of the enzymatically treated fibrous hamartoma tissue resulted in growth of the adherent fibroblast-like spindle cells. Expression of hundreds of genes including bone morphogenetic protein-2 and -4, and NF1 were screened by reverse transcription-polymerase chain reaction and cDNA array hydridization methods. RESULTS: Bone morphogenetic protein-2 and -4, and, NF1 were found to express in normal bone, normal periosteum as well as fibrous hamartoma and adjacent hypotrophic bone. Twenty-four genes were found to express exclusively in the fibrous hamartoma, and fifty genes only in the normal bone. CONCLUSION: These findings suggest that the causative gene of neurofibromatosis, NF1, may be associated with pathogenesis of the congenital pseudoarthrosis of the tibia in neurofibromatosis patients.