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学的颅面修复策略的关键一步。通过促进体内的同质分化和维持理想的分化状态，这些材料将提高细胞治疗的分化效率和安全性。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，我们的目标是使用一系列基于蛋白质的材料来研究软骨形成，在这些材料中，生化和生物物理性质是分离的，并且可以独立调节。具体地说，我们将结合Resilin的序列来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(即配体呈递和交联物密度)可用于调节间充质干细胞(MSC)的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，我们将设计出不同的材料，改变配体与材料的结合强度和配体的价态。第二个具体目标将确定生化环境是否调节维持软骨表型和防止肥大的最佳交联密度。这项工作的创新之处在于，我们利用重组蛋白质固有的高水平结构控制来研究使用其他材料不易实现的材料参数(例如结合强度和价态)。这项研究的意义在于，这些以蛋白质为基础的材料将被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.