力学微环境对骨髓间充质干细胞分化、生长和力学结构的调控作用

The mechanical microenvironment of stem cells is very critical in regulating their biological behavior such as differentiation, proliferation, apoptosis and migration. But there are still lots of unknown problems about how the properties of cell-matrix adhesion and the mechanical stimulations mediate the above processes. Bone marrow mesenchymal stem cells (BMSC) are multipotent stem cells, and currently are the most commonly used stem cells in the field of tissue engineering and regenerative medicine. In this project, micropatterning technique will be used to control the adhesion area and cell shape of BMSC. Then the apoptosis and differentiation of cells will be studied. Fluorescent imaging will be used to obtain the structure of focal adhesion complexes, stress fibers, nucleus, which is further combined with the cell-matrix traction force measurement to reveal the cellular mechanics structure. In addition, the signal transduction pathway and the roles of the mechanical stimulations during the above regulation process will be studied. The research results of this project will be helpful to understand the relationship between the mechanical microenvironment of stem cells and their biological behavior, and ultimately provide the basis for the study of mechanism of developmental biology and tissue repair as well as for the practical application of tissue engineering and regenerative medicine.

干细胞的力学微环境对于调控干细胞的分化、增殖、凋亡、迁移等生物学行为具有重要作用，但细胞－基质间的粘附性质和力学刺激如何调控以上过程仍有许多未知问题。骨髓间充质干细胞是多分化潜能干细胞，并且是当前组织工程和再生医学领域最常用的干细胞。本项目将以骨髓间充质干细胞为研究对象，利用微模式化技术精确控制细胞的铺展面积和形状，进而观测细胞的分化和凋亡；再通过荧光观察获取粘附斑复合物、应力纤维、细胞核等分子或细胞器的结构，对图像进行处理并结合细胞－基质间牵引力测量结果进行细胞力学结构分析；还将研究影响此力学结构的信号转导通路以及力学刺激如何参与以上调控过程。通过此项目的研究，将可深入理解干细胞力学微环境与其生物学行为之间的关联性，并最终为发育生物学和组织修复方面的机制研究以及组织工程和再生医学领域的实际应用提供研究基础。

干细胞的力学微环境对于调控干细胞的分化、增殖、凋亡、迁移等生物学行为具有重要作用，但细胞－基质间的粘附性质和力学刺激如何调控以上过程仍有许多未知问题。本项目以细胞调控的骨重建为背景，主要研究单/多细胞-基质粘附形态对干细胞力学状态、分化和生长情况的影响。研究过程中应用模式化方法构建了具有不同铺展形状和面积的单细胞粘附环境以及具有不同铺展形状和基底刚度的多细胞粘附环境，检测细胞的分化、凋亡、力学信号转导、细胞极化方向、细胞骨架结构以及细胞与基底间的牵拉力等生物学行为。研究结果发现与培养于圆形基底的细胞相比，圆度较低的星形基底的单细胞更易于成骨向分化并可促进其存活，表明单细胞的形状（圆度）可以调控干细胞的分化方向及生长状态。关于铺展形状对分化和凋亡的控制机制研究，已经基于点扩散函数构建了提取微丝单根纤维及多根纤维结构参数的方法，同时发现β-catenin蛋白的核转移受到细胞铺展面积的影响。另外，关于多细胞单层的研究结果发现，铺展形状会显著影响细胞-基底间的力学相互作用，并影响单层内的力学状态，进而引起细胞中力学传递分子分布的变化，从而调控细胞的粘附及分化。以上结果进一步阐明了干细胞力学微环境对其生物学行为的调控作用，可为发育生物学和组织修复方面的机制研究以及组织工程和再生医学提供基础数据。