P2: Role of PTH in enhancing fracture repair in aging

P2：PTH 在增强老化骨折修复中的作用

• 批准号: 7682121
• 负责人: Regis J O'Keefe
• 金额: $ 26.68万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7682121
• 关键词: Affect; Age; Aging; Allografting; Biomechanics; Bone Regeneration; Bone callus; Cartilage; Cells; Chondrocytes; Chondrogenesis; Clinical Data; Data; Fracture; Fracture Healing; Gene Expression; Healed; Hypertrophy; Impaired wound healing; Modeling; Mus; PTGS2 gene; PTHLH gene; Periosteal Cell; Periosteum; Process; Role; Signal Pathway; Staging; Stem cells; Testing; Tissues; Transforming Growth Factor beta; Transgenic Mice; Vascularization; age related; aged; base; cyclooxygenase 2; healing; improved; juvenile animal; mineralization; parathyroid hormone-related protein; repaired

The project is based on preliminary data showing an age-related quantitative decline in fracture healing in a murine model, with reproducible findings of delayed chondrogenesis and subsequent chondrocyte hypertrophy. In addition vascularization and remodeling of the mineralized cartilage is diminished. In conjunction with this, a decline in smurf2 expression in fracture callus occurs with aging, as well as a decline in COX-2 expression. Given the known effect of smurf2 on enhancing chondrocyte maturation and mineralization, and preliminary data indicating stimulation of smurf2 expression by PTH, the effects of PTH on restoring smurf2 expression and enhancing healing of fractures in aging mice will be evaluated. Determination of the role of the target cells of the periosteum will also be investigated using allografting with periosteal cells from genetically marked donor mice. The Specific Aims are: 1. Comprehensive quantitative characterization of fracture healing in young and aging mice using histomorphometry, microCT, and biomechanical analysis will be correlated with gene expression, with focus on TGF-beta/BMP and PTH/PTHrP signaling pathways. 2. Determining the differences in the capacity of periosteal stem cells from young and old mice to initiate bone repair and the roles of COX2 and PTHrP. The reparative potential of periosteum in young and old mice will be evaluated to determine if tissue from young animals can restore fracture healing in aged mice. Based on known loss of COX-2 with aging and impaired healing in Cox-2 -/- mice, effects of periosteum from COX-2 -/- and COX-2 +/- on healing in young and old mice will be evaluated. Finally, periosteum from coHAIPTHR transgenic mice will be evaluated in aging mice to determine if PTH/PTHrP signal pathway activation can restore healing in COX-2 -/- or aging mice. Healing will be evaluated by microCT, histomorphometry, and biomechanical testing in all cases. 3. Defining the effect of PTH during the various stages of fracture repair in aged mice. Despite data and clinical use of PTH in fracture healing stimulation, there is not a clear understanding of the mechanisms involved or stage of the repair process affected by PTH. The ability to improve fracture repair in aged mice, and ability of PTH to compensate for the loss of Cox-2 will be evaluated. Effects on smurfl and 2 expression during fracture healing, about which little is currently known, will also be investigated.

该项目基于的初步数据显示，骨折愈合数量随年龄而下降。 小鼠模型，具有可重复的延迟软骨形成和随后的软骨细胞的发现 肥大。此外，矿化软骨的血管形成和重塑也减少。在 与此同时，骨折愈伤组织中 smurf2 的表达随着年龄的增长而下降，并且随着年龄的增长而下降 COX-2 表达。鉴于 smurf2 对促进软骨细胞成熟的已知作用 矿化，初步数据表明 PTH 刺激 smurf2 表达，PTH 的影响 将评估恢复 smurf2 表达和促进衰老小鼠骨折愈合的作用。 还将使用同种异体移植来研究确定骨膜靶细胞的作用 来自基因标记的供体小鼠的骨膜细胞。具体目标是： 1. 使用年轻和老年小鼠骨折愈合的综合定量表征 组织形态计量学、显微 CT 和生物力学分析将与基因表达相关，重点关注 TGF-β/BMP 和 PTH/PTHrP 信号通路。 2. 确定年轻和年老小鼠骨膜干细胞能力的差异 启动骨修复以及 COX2 和 PTHrP 的作用。年轻人和青少年骨膜的修复潜力 将评估年老小鼠，以确定年轻动物的组织是否可以恢复老年小鼠的骨折愈合 老鼠。根据 Cox-2 -/- 小鼠中已知的随着衰老和愈合受损而丧失的 COX-2， 将评估来自 COX-2 -/- 和 COX-2 +/- 的骨膜对年轻和年老小鼠愈合的影响。最后， coHAIPTHR 转基因小鼠的骨膜将在衰老小鼠中进行评估，以确定 PTH/PTHrP 是否 信号通路激活可以恢复 COX-2 -/- 或衰老小鼠的愈合。愈合情况将通过以下方式进行评估 所有病例均进行显微 CT、组织形态测量和生物力学测试。 3. 确定 PTH 在老年小鼠骨折修复各个阶段的作用。 尽管有数据和临床上 PTH 在骨折愈合刺激中的应用，但仍没有明确的认识 受 PTH 影响的修复过程的机制或阶段。改善骨折的能力 将评估老年小鼠的修复，以及 PTH 补偿 Cox-2 损失的能力。对的影响 骨折愈合过程中smurfl和2的表达目前知之甚少，也将被 调查了。