TGF-beta in the pathology and development of the spine

描述（由申请人提供）：发育生物学是研究具有专门功能的细胞如何从未分化的细胞中衍生出来，以及细胞如何相互作用并与环境相互作用，最终形成组织和器官。因此，了解骨骼发育的基本机制是非常重要的，如果我们要在工程化骨骼组织方面取得进展。TGF-β超家族的成员是分泌的信号蛋白，其调节发育和组织稳态的许多方面，包括生长、图案化和细胞分化。人类Tgfb基因的多态性和突变与成人脊柱的病理学有关，以前，我们使用基因工程小鼠模型表明Tgfbr 2是椎间盘（IVD）发育和维持所必需的。我们的结果表明：1）TGF-β在发育中轴骨的边界形成中是必需的; 2）TGF-β阻止软骨的形成并促进胚胎间充质中IVD细胞的形成。在本修订（补充）申请中，我们将检验以下假设：TGF-β和BMP的梯度对间充质祖细胞具有阈值效应，导致沿着软骨或IVD谱系分化，从而在中轴骨骼中的两种细胞类型之间产生清晰的边界。我们提出使用可以模拟天然细胞外基质（ECM）的基本性质的仿生自组装纳米基质来模拟TGF-β介导的边界形成和中轴骨骼中的细胞分化模式。该纳米基质由合成肽-两亲物（PA）制成，并含有以下性质：1）在生理条件下快速形成三维网络，2）提供细胞附着的细胞粘附部分，和3）用于基质重塑的酶介导的可降解位点。纳米基质可以被工程化以在整个基质中或以区域/梯度模式含有生长因子。因此，纳米基质可以提供模拟细胞外基质（ECM）的环境，并且可以用作研究组织发育的模板。对骨骼系统如何发育的清楚理解将对组织工程策略产生直接影响。发育生物学和生物工程学之间的这种伙伴关系将为未来旨在修复或再生椎间盘的策略提供基础。

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.