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.

合作项目的指导研究策略是使用削弱疾病的临床前模型 与VA人群高度相关的骨或延迟骨折修复，采用体内/体外模型 确定“可用药”的机制，从而能够测试针对这些机制的有希望的治疗方法，同时 利用该小组的综合专业知识纳入最佳方法和成果衡量标准。骨折， 尤其是骨折延迟或不愈合，是我们的发病率和生产力损失的主要原因 退伍军人。需要更好的治疗。甲状旁腺激素(PTH)治疗有望加速 骨折修复和闭合骨不连。我们以前的研究表明，IGF1信号转导是 甲状旁腺素的合成代谢作用，而IGF1的作用又依赖于ewitinB2/EphB4的双向作用 发信号。阿巴拉肽是甲状旁腺激素的类似物，它对骨骼的合成代谢似乎比甲状旁腺素更强。但这些是如何 合成代谢药物实际上促进骨折修复的作用尚不清楚，而且骨折修复过程本身也很复杂。我们 我专注于骨折的长骨骨痂内进行骨折修复的三个部位，每个部位 具有独特的特点。1)骨折端骨膜表面可见膜内骨形成 涉及骨膜成骨祖细胞向成骨细胞直接分化的皮质。2)软骨内骨 形成桥接骨断端之间的间隙，涉及骨膜骨软骨分化 祖细胞转化为软骨细胞，然后转化为成骨细胞，形成骨痂。3) 髓内骨形成发生在碎骨碎片的骨髓内，由一组独特的 骨细胞和潜在的跨皮质血管周围细胞表达干细胞标记物 皮质进入骨髓，分化(去分化)成成骨细胞，在骨髓内形成骨。我们 假设阿巴拉肽作用于这些不同的细胞，所有这些细胞都表达PTH/PTHrP受体 通过该机制，阿巴拉肽将通过包括IGF1在内的机制促进协调修复进程 调控骨祖细胞、软骨细胞、成骨细胞和血管周围细胞间的ePhinB2/EphB4偶联 骨折修复所必需的细胞。我们将使用各种机械、分子和成像手段 在我们自己的实验室和我们的合作者的VAMR协作式提案中检查响应 在这些地点中的每一个地点进行阿巴罗巴拉蒂。然后我们将在小鼠模型中测试这种反应，在该模型中IGF1 已经从参与骨折修复的细胞中删除了受体和ewitinB2，以测试这些因素的作用 阿巴拉定反应中的信号机制。我们的项目有三个目标。目标1将演示 阿巴拉肽是否通过IGF1/ewitinB2/EphB4信号通路促进骨折修复 通过使用微型计算机断层扫描测量骨形成速度来再生骨形成 评估结构，X射线计算机断层扫描评估矿物成分，组织形态计量学评估 细胞变化、评估基因组变化的信使核糖核酸水平、有限元分析和悬臂弯曲 以评估骨痂的强度。目的2将检查髓内骨在骨折修复中的作用 以及骨细胞在其形成中的作用与使用细胞耗竭的策略。目标3将使用血统追踪来 阿巴拉肽对骨膜和皮质骨中骨软骨前体细胞的激活作用 以及它们的后代随后参与不同修复部位的骨形成。目标4将 应用SPACE技术确定阿巴拉肽诱导修复过程中各部位的分子变化 转录学评估在骨折修复不同部位发生的基因组变化。