支架材料的表面形貌调控骨再生中干细胞成骨分化及机制的研究

Scaffold material is a key element of bone regeneration. Our previous studies showed that hydroxyapatite with the roughness of 0.77-1.09μm increased the osteogenic differentiation of mesenchymal stem cells from mouse, and increased the transcriptional activity of TAZ, the key factors of Hippo signaling pathway. Similar phenomena were also found from the materials of titanium and polycaprolactone. This indicates that scaffold materials can provide micro-environment for bone regeneration, and the specific surface topography of scaffold materials can induce osteogenic differentiation of stem cells with possible better safety and clinical application potential. However, the exact effect and mechanism of this new induction method has not been confirmed. This project plans to study the effects and mechanisms of the topography of scaffold on the osteogenic differentiation of mesenchymal stem cells in vitro; the effects and mechanisms of BM-MSC cultured in the scaffold with specific topography on the healing of cephalic defect in mice; and the effects and mechanisms of the increasing of the differentiation of mesenchymal stem cells with general culturing based on Hippo signaling. The purposes of this project are to define the exact effects and mechanisms of the topography on the osteogenic differentiation of mesenchymal stem cells, the effects and mechanisms of the topography on the osteogenic differentiation of mesenchymal stem cells based on the Hippo signaling pathway. This project is expected to provide a deeper understanding of the mechanism of the topography increasing the osteogenic differentiation of mesenchymal stem cells, and theoretic and experimental support for the design of the safer and more effective scaffold for bone regeneration.

支架材料是骨组织工程的核心问题之一。我们前期研究发现表面粗糙度为0.77-1.09μm的羟基磷灰石支架能促进干细胞的成骨分化；且明显激活细胞内Hippo信号关键因子TAZ的转录活性；并在钛、聚乙酸内酯材料上发现相似现象。这些结果提示支架材料除了提供骨再生的微环境，其特定的表面形貌还有诱导成骨分化的作用，这种新的诱导方式可能更具安全性和应用前景，但其确切的效应和机制尚未明确。本项目拟确定不同表面形貌的支架材料诱导成骨分化的效应；研究支架表面形貌通过Hippo信号调控成骨分化的分子机制；利用小鼠颅骨缺损模型研究不同表面形貌的支架材料及Hippo信号缺失的骨髓间充质干细胞修复颅骨缺损的效应及机制。本研究旨在明确支架表面形貌调控干细胞成骨分化的效应，阐明表面形貌调控成骨分化的分子机制并探索通过表面形貌优化骨再生的可行性，为设计更为安全有效的组织工程骨支架材料提供理论依据和实验依据。

支架材料是骨组织工程的核心问题之一, 其表面形貌具有促进成骨的能力。但其促进成骨的效应和机制尚不清楚。本研究中，我们发现：支架材料的表面形貌参数Ra和RSm在微米级范围内(Ra 0.77-1.09 μm; RSm 53.9 - 39.3 μm)促进间充质干细胞的成骨分化；表面形貌通过上调Hippo信号关键分子TAZ的表达，激活成骨分化关键转录因子RUNX2转录，最终促进成骨成骨分化。TAZ全身敲除，激活破骨细胞，导致了小鼠骨质疏松表型；破骨细胞中特异性敲除TAZ,同样导致了骨质疏松表型。体外沉默和敲除TAZ，增强破骨细胞分化；过表达TAZ抑制破骨细胞分化。结果表明，特定的表面形貌可通过上调TAZ促进成骨分化，同时，TAZ可通过抑制破骨细胞分化及活性，在骨质疏松症的发生发展中发挥重要作用。本研究明确了支架表面形貌调控干细胞成骨分化的效应，阐明了表面形貌调控成骨分化的分子机制，为设计更为安全有效的组织工程骨支架材料提供了理论依据和实验依据。另外,本研究明确了TAZ抑制破骨细胞分化，阐明了TAZ在骨质疏松症的发生发展中所起的重要作用.为临床治疗骨质疏松症提供了潜在的靶点。