Notch signaling and Bone Fracture Healing

Notch信号传导和骨折愈合

• 批准号: 10589870
• 负责人: Kurt David Hankenson
• 金额: $ 56.1万
• 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/10589870
• 关键词: Acceleration; Agonist; BMP2 gene; Bone Injury; Bone Regeneration; Bone callus; Bypass; Cell Differentiation process; Cell Lineage; Cells; Cephalic; Chondrocytes; Clinical; Complement; Complex; Data; Defect; Development; Endothelial Cells; Endothelium; Ensure; Environment; Femoral Fractures; Femur; Fracture; Gene Expression; Generations; Goals; Histology; Impaired healing; Impairment; Injury; Joints; Laboratories; Laboratory Study; 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; Proliferating; 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; inducible Cre; 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.

紧急临床需要开发新的治疗剂来促进骨骼的愈合。虽然大多数 骨骼损伤愈合，许多人没有，尤其是大缺陷。了解细胞信号传导机制 调节正常的愈合，可能导致我们达到新的治疗靶点。 Notch信号传导调节膨胀和 间质祖细胞（MPC）的分化，并调节许多组织的血管形成， 包括骨头。我们的研究并发表了其他研究人员的研究，表明Notch信号是一种 骨骼愈合过程中的关键调节途径。确实，我们的初步和发表的结果表明 增加MPC中的Notch信号传导可改善骨再生，并使用Notch的全局抑制 各种模型，有害影响康复。充分提高了我们对Notch信号的理解 在骨骼愈合和翻译这些机械观察中，将需要强大的实验，包括 相关伤害模型中的临床前研究。我们的长期目标是开发一种与临床相关的方法 增加凹口信号，以增强骨骼愈合。 我们假设Notch信号促进了MPC和愈伤组织血管的扩张， 增强骨形成。我们将在骨骼愈合过程中询问Notch信号通路，以揭示 对愈合过程中正在发挥作用的配体和受体的更深入了解，细胞类型的特异性 这些信号传导组件的表达。这项工作将以两个特定的目的完成，使用 艺术鼠标模型。在第一个目标中，我们将研究Notch配体的作用。我们的工作以前有 证明JAGGED1是MPC和骨软骨的主要缺口配体 血统。我们将在MPC，软骨细胞，成骨细胞和骨细胞中特别破坏JAG1 在断裂愈合期间。另外，作为内皮细胞产生的JAG1和DLL4调节血管， 我们将确定使用两者的条件缺失的主要配体调节血管化的配体 使用CDH5-CREER来自内皮细胞的配体。一系列骨折治愈结果，包括 血管形成以及对内皮细胞和MPC增殖和MPC分化的影响将是 确定体内。我们将利用诱导CRE小鼠来利用我们的丰富经验，以确保正常 发展，从而涵盖了配体破坏的发育效果。这些研究将是 补充了一项翻译研究，其中JAG1蛋白单独或与现有 疗法BMP2将在关键大小股骨缺陷的愈合过程中进行。在第二个目标中，我们将 使用Notch1或Notch2 Floxed小鼠检查Notch受体在MPC和内皮细胞上的作用。我们 将确定这些受体对于由BMP2或JAG1驱动的缺陷愈合至关重要。这项研究会 通过阐明骨愈合过程中配体和受体的细胞特异性作用来显着推进该领域， 并提供临床前的相关性，以使局部激活Notch信号传导增加骨缺损愈合。