Study of osteogenetic effect on the fracture callus of facial bone by LRP5 gene transfer

Wnt家族是一组生长因子，在早期胚胎发生的几乎所有阶段都发挥重要作用。最近对编码Wnt共受体的LRP 5基因破坏的小鼠的研究表明，LRP 5/Wnt/β-连环蛋白信号在骨软骨形成和骨代谢中的重要性。因此，假设β-连环蛋白信号通路的激活将促进修复过程中的骨软骨形成。在本研究中，我们选择了激活β-catenin信号通路的Wnt家族中的Wnt 3a基因作为转基因，并使用Wnt 3a基因表达载体作为基因转移载体。我们通过电穿孔将Wnt 3a基因导入骨折附近的组织中，这比通过病毒载体的基因转移更安全，但效率更低，并且当在特定条件下进行时，它导致了相对高效率的基因表达。我们研究了Wnt 3a基因转移对骨痂的影响，骨痂是骨折愈合过程中出现的鞘样结构。骨痂由成纤维细胞、软骨细胞和成骨细胞组成，这些细胞是由未分化的间充质细胞分化而来的。Wnt 3a基因的引入激活了Wnt/β-连环蛋白信号通路，并促进了软骨的分化，如通过骨痂体积的增加所观察到的，这在骨折修复中起关键作用。未来的研究多方面的评估骨后，通过电穿孔Wnt 3a基因的引入将是必要的。本研究表明，添加Wnt 3a增加了骨痂的体积，这些结果可能有助于开发新的治疗模式，用于诱导骨缺损患者的骨再生。

The Wnt family is a group of growth factors that play an important role in almost all stages of early embryogenesis. A recent study on mice with disruption of the LRP5 gene, which encodes a co-receptor of Wnt, suggested the importance of the signal of LRP5/Wnt/β-catenin in osteochondrogenesis and bone metabolism. Accordingly, it is assumed that activation of the β-catenin signal pathway would promote osteochondrogenesis in the processes of repair. In the present study, as the transgene, we selected the Wnt3a gene in the Wnt family which activate the β-catenin signal pathway, and used a Wnt3a gene expression vector as the gene-transferring vector. We introduced the Wnt3a gene into tissue in the vicinity of bone fracture by electroporation, which is safer although less efficient than gene transfer by a viral vector, and it resulted in gene expression with relatively high efficiency when conducted under specific conditions. We investigated the effects of gene transfer of Wnt3a on the callus, which is a sheath-like structure that emerges during the healing process of bone fracture. The callus consists of fibroblasts, chondrocytes and osteoblasts that had differentiated from undifferentiated mesenchymal cells.Introduction of the Wnt3a gene into tissue in the proximity of bone fracture by electroporation exerted locally in an autocrine/paracrine manner. Introduction of the Wnt3a gene activated the Wnt/□β-catenin signaling pathway and promoted differentiation of cartilage as observed by an increase in the volume of the callus, which plays a key role in bone fracture repair. Future studies on multi-faceted assessment of bone upon introduction of the Wnt3a gene by electroporation will be required. The present study showed that the addition of Wnt3a increased the volume of the callus, and these results may be useful for developing new treatment modalities for induction of bone regeneration in patients with its defect.