TGF-beta in the pathology and development of the spine

描述(申请人提供)：发育生物学是研究如何从未分化的细胞中衍生出具有特殊功能的细胞，以及细胞如何相互作用并最终形成组织和器官。因此，如果我们要在骨组织工程方面取得进展，了解骨骼发育的基本机制是很重要的。转化生长因子-生长因子超家族的成员是分泌的信号蛋白，调节发育和组织动态平衡的许多方面，包括生长、模式和细胞分化。人类TGFb基因的多态和突变与成人脊柱的病理有关，在此之前，我们使用基因工程小鼠模型证明了TGFBR2是椎间盘(IVD)的发育和维护所必需的。我们的结果提示：1)在发育中的轴骨中，转化生长因子-ss是形成边界所必需的；2)转化生长因子-ss阻止了软骨的形成，并促进了胚胎间充质中IVD细胞的形成。在这一修订(补充)应用中，我们将检验这样一种假设，即转化生长因子-ss和骨形态发生蛋白的梯度对间充质祖细胞具有阈值效应，从而导致沿软骨或IVD谱系的分化，从而在中轴骨骼中产生两种细胞类型之间的尖锐边界。我们建议使用一种仿生的自组装纳米基质来模拟转化生长因子-生长因子-生长因子介导的边界形成和轴向骨骼中细胞分化的模式，这种纳米基质可以模拟自然细胞外基质的基本特性。该纳米骨架由合成肽-两亲性(PA)制成，具有以下特性：1)在生理条件下快速形成三维网络；2)细胞黏附部分提供细胞附着；3)酶介导的可降解部位用于基质重塑。纳米基质可以被设计成在整个基质中或在带状/梯度图案中包含生长因子。因此，纳米基质可以提供一个模拟细胞外基质(ECM)的环境，并可以作为研究组织发育的模板。清楚地了解骨骼系统是如何发展的，将对组织工程战略产生直接影响。发育生物学和生物工程之间的这种合作关系将为未来旨在修复或再生光盘的战略提供基础。

DESCRIPTION (provided by applicant): Developmental biology is the study of how cells with specialized functions are derived from undifferentiated cells and how cells interact with each other and their environment to ultimately form tissues and organs. Therefore, it is important to understand the basic mechanisms of development in the skeleton if we are to make progress in engineering skeletal tissue. Members of the TGF-ss superfamily are secreted signaling proteins that regulate many aspects of development and tissue homeostasis including growth, patterning, and cellular differentiation. Polymorphisms and mutations in human Tgfb genes have been associated with pathology in the adult spine and previously, we showed using genetically engineered mouse models that Tgfbr2 is required for development and maintenance of the intervertebral disc (IVD). Our results suggested that 1) TGF-ss is required for boundary formation in the developing axial skeleton and 2) TGF-ss prevents formation of cartilage and promotes the formation of IVD cells in embryonic mesenchyme. In this revision (supplement) application, we will test the hypothesis that gradients of TGF-ss and BMP have threshold effects on mesenchymal progenitors resulting in differentiation along either cartilage or IVD lineages thereby generating a sharp boundary between the two cell types in the axial skeleton. We propose to model TGF-ss mediated boundary formation and the pattern of cellular differentiation in the axial skeleton using a biomimetic self- assembled nanomatrix that can mimic essential properties of natural extracellular matrix (ECM). The nanomatrix is made from a synthetic peptide-amphiphile (PA) and contains the following properties: 1) rapid three-dimensional network formation at physiological conditions 2) cell adhesive moieties to provide cell attachment, and 3) enzyme-mediated degradable sites for matrix remodeling. The nanomatrix can be engineered to contain growth factors throughout the matrix or in a zonal/gradient pattern. Therefore, the nanomatrix can provide an environment that mimics the extracellular matrix (ECM) and can be used as a template for studying tissue development. A clear understanding of how the skeletal system develops will have a direct impact on tissue engineering strategies. Partnerships like this, between developmental biology and bioengineering, will provide a basis for future strategies aimed at disc repair or regeneration.