Protein-based Cartilage Matrices to Promote Mesenchymal Stem Cell Differentiation

描述（由申请人提供）：设计具有引导干细胞分化为软骨细胞的线索的材料是开发基于组织工程的颅面修复策略的关键步骤。通过促进均匀分化和维持体内所需的分化状态，这些材料将提高分化效率和基于细胞的治疗的安全性。长期目标是建立增强或指导成体干细胞分化的材料特性的一般设计规则。为了实现这一目标，我们的目标是研究软骨形成使用一个家庭的蛋白质为基础的材料，其中的生物化学和生物物理特性是解耦的，可以独立调整。具体地说，我们将从节枝弹性蛋白序列赋予所需的机械性能。我们还将在材料中设计蛋白质-蛋白质相互作用，以调节生化线索的呈现。我们的中心假设是，材料特性（即配体呈递和交联密度）可用于调节间充质干细胞（MSC）软骨形成和软骨细胞肥大。在第一个具体目标中，我们将研究配体呈递对软骨分化的影响。通过蛋白质工程，我们将工程材料，改变配体的结合强度的材料和配体的化合价。第二个具体目标将确定生物化学背景是否调节维持软骨表型并防止肥大的最佳交联密度。这项工作的创新之处在于，我们使用重组蛋白固有的高水平结构控制来研究使用其他材料不容易实现的材料参数（例如结合强度和化合价）。这项研究的意义在于，这些蛋白质基材料将用于建立软骨促进材料的一般设计原则。

DESCRIPTION (provided by applicant): Designing materials with cues that direct stem cell differentiation into cartilage cells is a key step in developing tissue-engineering based strategie for craniofacial repair. By contributing to homogeneous differentiation and maintaining the desired differentiation state in vivo, these materials would increase the efficiency of differentiation and safety of cell-based therapies. The long-term goal is to establish general design rules for material properties that enhance or direct adult stem cell differentiation. To achieve this goal, the objective is to investigate chondrogenesis using a family of protein-based materials in which the biochemical and biophysical properties are decoupled and can be independently tuned. Specifically, we will incorporate sequences from resilin to confer the desired mechanical properties. We will also engineer protein-protein interactions within the material to modulate presentation of biochemical cues. Our central hypothesis is that material properties (i.e. ligand presentation and crosslinking density) can be used to modulate both mesenchymal stem cell (MSC) chondrogenesis and chondrocyte hypertrophy. In the first specific aim, we will investigate the effect of ligand presentation on cartilage differentiation. Through protein engineering, we will engineer materials that vary the binding strength of the ligand to the material and the valency of the ligand. The second specific aim will determine whether biochemical context modulates the optimal crosslinking density that maintains the cartilage phenotype and prevents hypertrophy. The innovation of this work is that we use the high level of structural control inherent in recombinant proteins to investigate materials parameters (e.g. binding strength and valency) that would not easily be achieved using other materials. The significance of the proposed research is that these protein-based materials will be used in establishing general design principles for cartilage-promoting materials.