Nell-1调控Runx2/Osterix信号轴在种植体骨结合形成中的作用及机制研究

It is not clear about the mechanism how the roughened surface on dental implant promote bone marrow mesenchymal stem cells into osteoblasts to form osseointegration. Nell-1 is known having greater osteoinduction function than BMP2, and the study of Nell-1 related mechanism mostly concentrated in osteoporosis and repair of bone defect. Runx2 and Osterix are two key osteogenic transcription factors, can regulate the expression of bone related gene factors. This project presents Nell-1 can regulate the expression of Runx2/Osterix and has effect on the formation of osseointegration, and on this basis, through the construction of the overexpression and interference lentivirus vector, Nell-1 gene is transfected into BMSCs to investigate in the effect and mechanism of Nell-1 regulation of Runx2/Osterix signaling axis. Then we obtain genetically modified BMSCs cell sheet by light induced cell sheet techonology and culture on titanium surface to evaluate the effect and mechanism of the thin layer on implant osseointegration. This process can provide a new experimental basis and therapeutic target for the mechanism of implant osseointegration, to establish and maintain long-term implant osseointegration and provide scientific and reasonable theoretical support.

种植体粗化表面如何促进骨髓间充质干细胞成骨分化, 从而形成种植体骨结合，具体的形成机制尚不清楚。目前认识的Nell-1比BMP2更具有骨诱导作用，而Nell-1 相关机制的研究大都集中在骨质疏松、骨缺损修复等领域。Runx2和Osterix是两个关键的成骨转录因子，可调节成骨相关因子的表达。本项目提出了Nell-1可调控Runx2/Osterix的表达，并影响种植体骨结合的形成，并以此设想为基础，通过构建慢病毒过表达/干扰型载体将Nell-1基因转染进入BMSCs，探讨Nell-1调控Runx2/Osterix信号轴在种植体骨结合中的作用及机制；然后通过细胞薄层技术获得Nell-1转染的BMSCs薄层，并在钛片表面培养，体内外实验来评价该薄层在种植体骨结合中的作用及机制。本实验可为种植体骨结合机制提供新的实验依据和治疗靶点，为快速建立并长期维持种植体骨结合提供科学而合理的理论支持。

如何获得快速稳定的骨结合是当下口腔种植领域的研究热点，Nell-1具有良好的骨诱导能力，能够有效促进骨再生，但其在种植体骨结合形成过程中的作用及机制尚不明确。本研究成功构建Nell-1过表达及干扰慢病毒并将转染骨髓间充质干细胞（BMSCs），从正反两个方向证实了Nell-1能够有效促进BMSCs的成骨向分化，且这一作用是通过调控Runx2/Osterix信号轴实现的。在此基础上，在培养过程中不同时间点分别加入Runx2及Osterix的干扰病毒，发现Nell-1与Runx2/Osterix信号轴之间存在着反馈调节的作用。此后，通过构建Nell-1修饰的BMSCs膜片并制备膜片-种植体复合体，体内实验进一步证实了Nell-1能够提高种植体周围新骨形成率及种植体骨结合率。本研究的提出和完成，揭示Nell-1加快种植体骨结合形成的功能及相关机制，为进一步利用Nell-1，开发在口腔种植领域及头面部骨再生中的新型组织工程材料做好准备。