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，在早期胚胎发育的几乎所有阶段都发挥着重要作用。最近对编码Wnt共同受体的LRP5基因突变的小鼠的研究表明，LRP5/Wnt/β-catenin信号在骨软骨形成和骨代谢中具有重要作用。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Wnt家族中激活β-连环蛋白信号通路的Wnt3a基因作为转基因载体，并使用Wnt3a基因表达载体作为基因转移载体。我们通过电穿孔将Wnt3a基因导入骨折附近的组织中，这种方法比病毒载体转移基因更安全，但效率较低，并且在特定条件下进行基因表达时，基因表达效率相对较高。我们研究了WNT3a基因转移对骨痂的影响，骨痂是骨折愈合过程中出现的一种鞘状结构。骨痂由成纤维细胞、软骨细胞和未分化间充质细胞分化而来的成骨细胞组成。WNT3a基因以自分泌/旁分泌的方式局部电穿孔导入骨折近端组织。Wnt3a基因的导入激活了Wnt/-β-Catenin信号通路，促进了软骨的分化，表现为骨痂体积的增加，这在骨折修复中起着关键作用。通过电穿孔将WNT3a基因导入后，对骨骼进行多方面评估的未来研究将是必要的。本研究表明，WNT3a的加入增加了骨痂的体积，这些结果可能有助于开发新的治疗方法，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.