BCCMA:Foundational Research to Act Upon and Resist Conditions unfavorable to bone (FRACTURECURB):Role of abaloparatide for fracture healing

BCCMA：针对和抵抗不利于骨骼的条件的基础研究 (FRACTURECURB)：abaloparatide 在骨折愈合中的作用

• 批准号: 10584445
• 负责人: DANIEL David BIKLE
• 金额: --
• 依托单位: VETERANS AFFAIRS MED CTR SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-10-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10584445
• 关键词: Acceleration; Affect; Anabolic Agents; Bone Marrow; Bone callus; Cells; Characteristics; Chondrocytes; Complex; Coupling; Disease model; Ephrin-B2; Event; Finite Element Analysis; Fracture; Genomics; IGF1 gene; Image; Injury; Invaded; Laboratories; Marrow; Measures; Mechanics; Mediating; Messenger RNA; Methods; Minerals; Modeling; Molecular; Morbidity - disease rate; Osteoblasts; Osteocytes; Osteogenesis; Outcome Measure; PTH gene; Parathyroid Hormone Receptor; Pathway interactions; Pericytes; Periosteum; Population; Pre-Clinical Model; Process; Productivity; Proliferating; Research; Role; Signal Transduction; Site; Structure; Surface; Testing; Veterans; X-Ray Computed Tomography; analog; bone; bone fracture repair; cantilever; cortical bone; directed differentiation; effectiveness evaluation; in vitro Model; in vivo; intramembranous bone formation; long bone; migration; military veteran; mortality; mouse model; novel; osteochondral tissue; osteoprogenitor cell; parathyroid hormone-related protein; progenitor; receptor; regenerative; repaired; response; stem cell biomarkers; stem cells; tomography; transcriptome sequencing; transcriptomics; transdifferentiation

The guiding research strategy of the collaborative projects is to use pre-clinical models of disease that weaken bone or delay fracture repair of high relevance to the VA population, employing in vivo/in vitro models to identify ‘druggable’ mechanisms enabling the testing of promising therapies directed at those mechanisms, while incorporating best methods and outcome measures utilizing the combined expertise of the group. Fractures, and in particular delayed or non union of fractures, is a major cause of morbidity and lost productivity in our Veterans. Better treatment is required. Parathyroid hormone (PTH) treatment shows promise in accelerating fracture repair and closing non unions. Our previous studies demonstrated that IGF1 signaling is required for the anabolic actions of PTH, and that the actions of IGF1 are in turn dependent on ephrinB2/EphB4 bidirectional signaling. Abaloparatide is an analog of PTH that appears even more anabolic to bone than PTH. But how these anabolic agents actually promote fracture repair is unclear, and the fracture repair process is itself complex. We have focused on three sites at which fracture repair takes place within the callus in fractured long bones, each with unique characteristics. 1) Intramembranous bone formation occurs on the periosteal surface of the fractured cortex involving direct differentiation of periosteal osteoprogenitors to osteoblasts. 2) Endochondral bone formation bridges the gap between the broken ends of bone involving differentiation of periosteal osteochondroal progenitors into chondrocytes which then transdifferentiate into osteoblasts forming the bony callus. 3) Intramedullary bone formation occurs within the marrow of the broken bone pieces initiated by a unique set of osteocytes and potentially transcortical vessel perivascular cells expressing stem cell markers that move from the cortex into the marrow to differentiate (dedifferentiate) into osteoblasts forming bone within the marrow. We hypothesize that abaloparatide, acting on these different cells, all of which express the PTH/PTHrP receptor through which abaloparatide acts, will promote the coordinated repair process via mechanisms that include IGF1 regulated ephrinB2/EphB4 coupling between the osteoprogenitors, chondrocytes, osteoblasts, and perivascular cells essential for fracture repair. We will use a variety of mechanical, molecular, and imaging means established in our own laboratory and that of our collaborators in the collaborative VAMR proposal to examine the response to abaloparatide at each of these sites. We will then test this response in mouse models in which the IGF1 receptor and ephrinB2 have been deleted from the cells involved with fracture repair to test the role of these signaling mechanisms in the response to abaloparatide. Our project has three aims. Aim 1 will demonstrate whether abaloparatide accelerates fracture repair via IGF1/ephrinB2/EphB4 signaling at each site of regenerative bone formation by measuring the rate of bone formation using microcomputed tomography to assess structure, Xray computed tomography to assess mineral composition, histomorphometry to evaluate cellular changes, mRNA levels to assess genomic changes, and finite element analysis and cantilever bending to evaluate the strength of the callus. Aim 2 will examine the contribution of intramedullary bone to fracture repair and the role of osteocytes in its formation with the use cell depletion strategies. Aim 3 will use lineage tracing to demonstrate the activation of osteochondral progenitors in the periosteum and cortical bone by abaloparatide and the subsequent involvement of their progeny in bone formation at the different sites of repair. Aim 4 will determine the molecular changes at each site during the repair process induced by abaloparatide using spatial transcriptomics to evaluate the genomic changes occurring in the different site of fracture repair.

协作项目的指导研究策略是使用虚弱的疾病前临床模型 使用体内/体外模型的骨头或延迟与VA种群高相关性的骨折修复 确定“可毒”的机制，可以测试针对这些机制的承诺疗法，而 利用该小组的组合专业知识纳入最佳方法和结果度量。骨折， 尤其是骨折的延迟或非碰撞，是发病率和生产力失去的主要原因 退伍军人。需要更好的治疗。甲状旁腺激素（PTH）治疗表明加速有望 断裂修复和关闭非工会。我们先前的研究表明，IGF1信号是需要的 PTH的合成代谢作用，而IGF1的作用又取决于ephrinb2/ephb4双向 信号。鲍多吡啶胺是PTH的类似物，比骨骼比PTH更合成代谢。但是这些 合成代谢剂实际上促进断裂修复尚不清楚，并且断裂修复过程本身是复杂的。我们 专注于三个部位，在愈伤组织内进行骨折修复的三个位置，每个骨折的长骨头都 具有独特的特征。 1）膜内骨形成发生在骨折的骨膜表面 皮质涉及将骨膜骨基因生成剂直接分化为成骨细胞的皮质。 2）软骨内骨 地层桥接骨头破裂的末端之间的缝隙涉及骨膜骨软骨的分化 祖细胞中的祖细胞转变为形成骨愈伤组织的成骨细胞。 3） 髓内骨形成发生在由一组独特的骨头的骨髓中 骨细胞和潜在的跨皮层血管周围血管细胞表达从移动的干细胞标记 将皮质进入骨髓，以区分（脱脂）成成骨细胞，形成骨髓内的骨骼。我们 假设作用在这些不同细胞上的鲍巴吡啶胺表达PTH/PTHRP受体 鲍多吡啶酯的作用将通过包括IGF1在内的机制促进协调的维修过程 在骨基因生成剂，软骨细胞，成骨细胞和周围的骨核基构体之间偶联的Ephrinb2/ephb4耦合 细胞对断裂修复必不可少的细胞。我们将使用已建立的各种机械，分子和成像手段 在我们自己的实验室和合作者中的合作者中，可以检查响应 到这些地点的每个地点。然后，我们将在IGF1的鼠标模型中测试此响应 接收器和埃菲林B2已从骨折修复所涉及的细胞中删除，以测试这些作用 对鲍鱼剂的反应中的信号传导机制。我们的项目有三个目标。 AIM 1将证明 鲍多拉丁是否通过在每个位置的IGF1/ephrinb2/ephb4信号来加速骨折修复 通过使用微型层析成像来测量骨形成速率，再生骨形成 评估结构，X射线计算机断层扫描以评估矿物组成，组织形态计量学以评估 细胞变化，评估基因组变化的mRNA水平以及有限元分析和悬臂弯曲 评估愈伤组织的强度。 AIM 2将检查髓内骨骼对断裂修复的贡献 以及骨细胞与使用细胞耗竭策略形成的作用。 AIM 3将使用谱系跟踪 证明鲍巴拉肽在骨膜和皮质骨中的骨软骨祖细胞的激活 以及随后其后代参与不同修复部位的骨形成。目标4意志 在使用空间的鲍多拉底剂引起的修复过程中，确定每个位点的分子变化 转录组学评估在裂缝修复的不同部位中发生的基因组变化。