Notch signaling and Bone Fracture Healing

Notch信号传导和骨折愈合

• 批准号: 10363359
• 负责人: Kurt David Hankenson
• 金额: $ 58.74万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10363359
• 关键词: Agonist; BMP2 gene; Bone Injury; Bone Regeneration; Bone callus; Cell Differentiation process; Cell Lineage; Cells; Cephalic; Chondrocytes; Clinical; Complement; Complex; Data; Defect; Development; Endothelial Cells; Endothelium; Ensure; Environment; Femoral Fractures; Fracture; Gene Expression; Generations; Goals; Histology; Impaired healing; Impairment; Injury; Joints; Laboratories; Laboratory Study; Lead; Ligands; LoxP-flanked allele; Mechanics; Mesenchymal Differentiation; Mesenchymal Stem Cells; Modeling; Molecular Analysis; Molecular Target; Mus; Natural regeneration; Notch Signaling Pathway; Osteoblasts; Osteocytes; Osteogenesis; Outcome; Periosteum; Play; Process; Proteins; Publications; Publishing; Receptor Inhibition; Regulation; Regulatory Pathway; Research Personnel; Role; Signal Transduction; Source; Testing; Therapeutic; Time; Tissues; Translating; Vascularization; Work; bone; bone fracture repair; bone healing; cell type; clinically relevant; efficacy evaluation; experience; healing; improved; in vivo; jagged1 protein; long bone; mouse model; new therapeutic target; notch protein; novel therapeutics; pre-clinical; preclinical study; promoter; receptor; skeletal regeneration; stem cell proliferation; translational study

There is an urgent clinical need to develop new therapeutics to promote healing of bone. While most bone injuries heal, many do not, particularly large defects. Understanding cellular signaling mechanisms that regulate normal healing, can lead us to new therapeutic targets. Notch signaling regulates the expansion and differentiation of mesenchymal progenitor cells (MPC) and regulates vascularization of many tissues, including bone. Our studies, and published studies from other investigators, show that Notch signaling is a key regulatory pathway during bone healing. Indeed, our preliminary and published results show that increasing Notch signaling in MPCs improves bone regeneration, and that global inhibition of Notch using various models, deleteriously impacts healing. To sufficiently advance our understanding of Notch signaling in bone healing, and translate these mechanistic observations, will require robust experimentation, including preclinical studies in relevant injury models. Our long-term goal is to develop a clinically relevant approach to increase Notch signaling that enhances bone healing. We hypothesize that Notch signaling promotes expansion of MPCs and callus vascularization, leading to enhanced bone formation. We will interrogate the Notch signaling pathway during bone healing to reveal a deeper understanding of ligands and receptors that are at play during healing, and the cell-type specific expression of these signaling components. This work will be completed in two specific Aims, using state of the art mouse models. In the first Aim, we will study the role of Notch ligands. Our work has previously demonstrated that Jagged1 is the dominant Notch ligand expressed in MPCs and the osteochondrogenic lineage. We will disrupt Jag1 specifically in MPCs, chondrocytes, osteoblasts and osteocytes in the callus during fracture healing. Additionally, as Jag1 and Dll4 produced by endothelial cells regulate vascularization, we will determine which is the dominant ligand regulating vascularization using conditional deletion of both ligands from endothelial cells using Cdh5-CreER. A spectrum of fracture healing outcomes, including vascularization, as well as effects on endothelial cell and MPC proliferation and MPC differentiation will be determined in vivo. We will capitalize on our extensive experience using inducible Cre mice to ensure normal development thereby by-passing developmental effects of ligand disruption. These studies will be complemented with a translational study in which Jag1 protein, alone or in combination with an existing therapy, BMP2, will be delivered during healing of critical sized femoral defects. In the second Aim, we will examine the role of Notch receptors on MPC and endothelial cells using Notch1 or Notch2 floxed mice. We will determine whether these receptors are critical for defect healing driven by BMP2 or Jag1. This study will significantly advance the field by clarifying the cell-specific role of ligand and receptor during bone healing, and provide the preclinical relevance for local activation Notch signaling to increase bone defect healing.

临床迫切需要开发新的疗法来促进骨愈合。虽然大多数 骨伤很多都不能愈合，特别是大的缺损。了解细胞信号传导机制 调节正常愈合，可以引导我们找到新的治疗目标。 Notch信号调节扩张和 间充质祖细胞（MPC）的分化并调节许多组织的血管化， 包括骨头。我们的研究以及其他研究人员发表的研究表明，Notch 信号传导是一种 骨愈合过程中的关键调控途径。事实上，我们的初步和公布的结果表明 增加 MPC 中的 Notch 信号传导可改善骨再生，并且使用 Notch 进行全局抑制 各种模型，对愈合产生有害影响。充分增进我们对 Notch 信号传导的理解 在骨愈合中，并转化这些机械观察结果，将需要强有力的实验，包括 相关损伤模型的临床前研究。我们的长期目标是开发一种临床相关的方法 增加Notch信号，增强骨骼愈合。 我们假设 Notch 信号传导促进 MPC 的扩张和愈伤组织血管化，从而导致 以增强骨形成。我们将在骨愈合过程中探究 Notch 信号通路，以揭示 更深入地了解在愈合过程中发挥作用的配体和受体，以及细胞类型特异性 这些信号成分的表达。这项工作将在两个具体目标中完成，利用状态 艺术鼠标模型。在第一个目标中，我们将研究Notch配体的作用。我们的工作之前 证明 Jagged1 是在 MPC 和骨软骨形成中表达的主要 Notch 配体 血统。我们将专门破坏 MPC、软骨细胞、成骨细胞和愈伤组织中的骨细胞中的 Jag1 骨折愈合期间。此外，由于内皮细胞产生的 Jag1 和 Dll4 调节血管形成， 我们将通过条件删除两者来确定哪个是调节血管化的主要配体 使用 Cdh5-CreER 来自内皮细胞的配体。一系列骨折愈合结果，包括 血管化，以及对内皮细胞和 MPC 增殖和 MPC 分化的影响 体内测定。我们将利用我们使用诱导型 Cre 小鼠的丰富经验来确保正常 从而绕过配体破坏的发育影响。这些研究将 补充一项翻译研究，其中 Jag1 蛋白单独或与现有的组合 BMP2 疗法将在严重股骨缺损的愈合过程中进行。在第二个目标中，我们将 使用 Notch1 或 Notch2 floxed 小鼠检查 Notch 受体对 MPC 和内皮细胞的作用。我们 将确定这些受体对于 BMP2 或 Jag1 驱动的缺损愈合是否至关重要。这项研究将 通过阐明配体和受体在骨愈合过程中的细胞特异性作用，显着推进了该领域的发展， 并提供局部激活 Notch 信号传导的临床前相关性，以促进骨缺损愈合。