Role of spatial heterogeneous matrix stifness in development of craniofacial tissue interfaces

项目摘要/摘要 研究表明，细胞外基质(ECM)的硬度决定了间充质的分化 干细胞(MSCs)附着在它上面。更硬的底物促进更硬的细胞系的分化[1]。 光降解水凝胶是一种新型的聚合物生物材料，由我们的团队在 加州大学洛杉矶分校。它们非常适合复制ECM[2，3]，并且在物理上和 化学上类似于ECM，具有很宽的弹性模数范围(~1-500千帕)。与众不同的 光降解水凝胶是指它们的交联度可以在外部改变，其中刚性是一个函数 光线强度和曝光时间的关系。这种生物材料可以复制复杂的、各向异性的和异质的 以亚微米分辨率模拟天然组织结构异质性的微环境。这 该项目建议通过设计和使用这种可光降解的水凝胶来促进组织工程 一种高精度的先进生物材料，具有五个维度的控制(三个空间维度，时间和内在 属性等级)。我意愿按顺序模仿天然组织界面中发现的图案和僵硬程度。 分析骨髓间充质干细胞的行为，提高对干细胞在体内去向的认识。 我打算创建的机械模式最终将复制所发现的固有的复杂环境 在自然界中，如发育中的牙齿和下颌突的骨-软骨界面。到目前为止， 基于ECM的干细胞研究还没有复制人体的极化结构到允许 理解细胞在这样的环境中的命运。这项研究计划旨在确定异质性 机械环境对2D和3D培养中的MSCs的影响随后回答以下问题： 包含决定干细胞命运的极化结构的微环境？如果我们设计一个环境来 模仿自然条件，干细胞会效仿吗？假设：可以使用光可调聚合物网络 通过诱导细胞对机械机械的反应来构建类似于天然组织的异质性结构 暗示。因为已经确定细胞分化可以在静态各向同性中被机械地触发 材料，在力学性能上具有空间差异的系统应该在 一种跨越多种长度和时间尺度的连续材料。我也希望除了控制牢房 表型，中间行为，如在自然组织界面发现的，将被观察到。

Project Summary/Abstract Research demonstrates that extracellular matrix (ECM) stiffness dictates the differentiation of the mesenchymal stem cells (MSCs) attached to it. Stiffer substrates promote the differentiation of stiffer cell lineages [1]. Photodegradable hydrogels are a novel class of polymeric biomaterials that have been developed by our group at University of California, Los Angeles. They are uniquely suited to replicate the ECM[2, 3] and are physically and chemically similar to the ECM, having a wide range of elastic moduli (~1-500 kPa). Distinctive of photodegradable hydrogels is that their cross-link density can be altered externally, where stiffness is a function of the light intensity and exposure time. This biomaterial can replicate complex, anisotropic, and heterogeneous microenvironments that mimic the structural heterogeneities of native tissue with sub-micron resolutions. This project proposes to advance tissue engineering through the design and use of this photodegradable hydrogel as a high-precision advanced biomaterial, with five degrees of control (three spatial dimensions, time and intrinsic property gradation). I intend to mimic patterns and stiffness gradations found in native tissue interfaces in order to analyze MSC behavior and advance the understanding of stem cell fate in vivo. The mechanical patterns I intend to create will ultimately replicate the inherently complex environments found in nature, such as the developing tooth and the bone-cartilage interface of the mandibular condyle. To date, ECM-based stem cell research has not replicated the body's polarized structures to a degree that allows for an understanding of cell fate in such environments. This research proposal intends to establish how heterogeneous mechanical environments impact MSCs in 2D and 3D culture to subsequently answer the following: Are microenvironments that contain polarized structures dictating stem cell fate? If we engineer an environment to mimic native conditions, will stem cells follow suit? Hypothesis: Photo-tunable polymer networks can be used to structure heterogeneities similar to those found native tissue by inducing a cellular response to mechanical cues. Since it has been established that cell differentiation can be triggered mechanically in static isotropic materials, a system with spatial differences in mechanical properties should trigger multiple cell lineages within a continuous material across a multitude of length and time scales. I also expect that beyond controlling cell phenotype, intermediate behavior, as found in native tissue interfaces, will be observed.