The Development of Treatment for Bone Defects in Maxilla Using Teflon Membran and the Analysis of Factors Promoting Maxillary Bone Regeneration

前列腺素(PG)是一类众所周知的炎症因子，已有报道称其中一些对骨骼有合成代谢作用。许多研究表明，PG，尤其是PGE_2在体内可增加松质骨和皮质骨的体积，并在体外促进成骨细胞分化。目前尚不清楚内源性PG是否以及如何与体内的骨形成相关。我们已经建立了一种大鼠模型，在该模型中，通过注射秋水仙素，可以在胫骨髓腔内看到成骨。利用这个模型，我们研究了环氧合酶(COX)基因的表达，COX基因是花生四烯酸中PG的合成酶，最近被发现有两种亚型，一种是结构型(COX-1)，另一种是诱导型(COX-2)。在成骨过程中，在成骨开始前的早期注射秋水仙碱后，COX-1和COX-2的基因表达增强。只有COX-2基因在骨形成开始后再次升高。此外，每日给予PG合酶抑制剂吲哚美辛可降低秋水仙碱诱导的大鼠胫骨骨量。这些数据表明，内源性PG与该模型中的成骨有关。此外，本研究提示COX-2和COX-1可能参与成骨细胞前体在成骨早期的诱导和增殖。COX-2可能更多地与成骨细胞在后期的成熟有关，而COX-1对骨成熟的贡献较小。

Prostaglandin (PG) is well-known as a group of inflammatory factors and some of them have been reported to have anabolic effects on bone. Many researchers have demonstrated that the administration of PG,especially PGE_2 increases the volume of trabecular and cortical bone in vivo and promotes the differentiation of osteoblast in vitro. It is still not clear whether and how endogenous PG is associated with bone formation in vivo. We have already established a rat model in which osteogenesis can be seen in the tibial medullary cavity by injecting colchicine. Using this model, we examined the expression of the cyclooxygenase (COX) gene that is the synthase of PG from arachidonic acid and has been recently revealed to have two subtypes, a constitutive type (COX-1) and an inducible one (COX-2). During the process of osteogenesis, the gene expression of COX-1 as well as COX-2 was enhanced after colchicine injection in the early stage before bone formation was started. Only the COX-2 gene was elevated again later during the beginning of bone formation. Furthermore, the daily administration of indomethacin, an inhibitor of PG synthase, could reduce the bone mass induced by colchicine in the rat tibiae. These data indicate that endogenous PG is associated with the osteogenesis in this model. Moreover, the present study suggests that COX-2 and COX-1 would be involved in the induction and proliferation of the osteoblast precursor during the early stage of osteogenesis. COX-2 is likely to be more associated with the maturation of osteoblasts in the later stage, while COX-1 will have less contribution to bone maturation.