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.

临床上迫切需要开发新的治疗方法来促进骨愈合。虽然大多数 骨损伤愈合，但许多不愈合，特别是大的缺损。了解细胞信号机制， 调节正常的愈合，可以引导我们找到新的治疗目标。Notch信号调节细胞的扩增， 间充质祖细胞（MPC）的分化并调节许多组织的血管形成， 包括骨头。我们的研究和其他研究人员发表的研究表明，Notch信号是一种 骨愈合过程中的关键调节途径。事实上，我们的初步和公布的结果表明， 增加MPC中的Notch信号传导改善了骨再生，并且使用 各种模型都会对愈合产生有害影响。为了充分推进我们对Notch信号的理解， 在骨愈合，并转化这些机制的观察，将需要强大的实验，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 来增加Notch信号，从而促进骨愈合。 我们假设Notch信号促进了MPC的扩增和骨痂血管化， 促进骨形成我们将在骨愈合过程中询问Notch信号通路，以揭示一种新的方法。 更深入地了解在愈合过程中起作用的配体和受体，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完成，使用状态 艺术老鼠模型。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 表明Jagged1是MPC中表达的主要Notch配体， 脉我们将在骨痂中的MPC、软骨细胞、成骨细胞和骨细胞中特异性地破坏Jag1。 在骨折愈合过程中。此外，由于内皮细胞产生的Jag 1和Dll 4调节血管形成， 我们将通过条件性删除两种配体来确定哪种是调节血管形成的主要配体， 使用Cdh5-CreER从内皮细胞中分离配体。一系列骨折愈合结局，包括 血管化，以及对内皮细胞和MPC增殖和MPC分化的影响将被 在体内测定。我们将利用我们使用诱导型Cre小鼠的丰富经验， 发育，从而绕过配体破坏的发育效应。这些研究报告将 补充了翻译研究，其中Jag1蛋白，单独或与现有的 治疗，BMP 2，将在关键尺寸的股骨缺损愈合过程中输送。在第二个目标中，我们将 使用Notch1或Notch2 floxed小鼠检测Notch受体在MPC和内皮细胞上的作用。我们 将确定这些受体是否对BMP 2或Jag 1驱动的缺陷愈合至关重要。本研究将 通过阐明骨愈合过程中配体和受体的细胞特异性作用， 并为局部激活Notch信号传导提供临床前相关性以增加骨缺损愈合。