Bone Abnormalities & Healing Defect in Muscular Dystrophy

骨骼异常

• 批准号: 9263882
• 负责人: Johnny Huard
• 金额: $ 33.88万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-06 至 2019-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9263882
• 关键词: 6 year old; Affect; Age; Aging; Animal Model; Animals; Applications Grants; Biomimetics; Birth; Blood Circulation; Cardiomyopathies; Cell Compartmentation; Cell physiology; Cells; Cessation of life; Congenital musculoskeletal anomalies; Data; Defect; Deformity; Disease; Disease Progression; Duchenne muscular dystrophy; Dystrophin; Exhibits; FGF2 gene; Fracture; Functional disorder; Goals; Heart failure; Hereditary Disease; Heterotopic Ossification; Histopathology; Homeostasis; Impaired wound healing; Individual; Infiltration; Intervertebral disc structure; Knock-out; Knockout Mice; Limb structure; Longevity; Mesenchymal Stem Cells; Modeling; Morphology; Mus; Muscle; Muscle Weakness; Muscular Atrophy; Muscular Dystrophies; Musculoskeletal; Myocardium; Myopathy; Nature; Osteopenia; Pathology; Patients; Phenotype; Play; Proteins; Quality of life; Rejuvenation; Reporting; Respiratory Failure; Role; Series; Skeletal Muscle; Skeletal system; Spinal; Stem cells; Teenagers; Tissues; Utrophin; Wheelchairs; Wild Type Mouse; Work; adult stem cell; articular cartilage; bone; bone healing; exhaustion; experience; experimental study; fragility fracture; healing; improved; improved functioning; inhibitor/antagonist; innovation; juvenile animal; mouse model; muscle degeneration; osteogenic; premature; prevent; public health relevance; regenerative; repaired; sarcopenia; scoliosis; skeletal; skeletal abnormality; skeletal muscle wasting; stem cell niche; theories

DESCRIPTION (provided by applicant): Duchenne Muscular Dystrophy (DMD) is a degenerative muscle disorder characterized by a lack of dystrophin expression that ultimately results in cardiac or respiratory failure. DMD patients also acquire osteopenia, fragility fracture, and scoliosis indicating that a deficiency in skeletal system homeostasis also occurs in DMD patients. It is speculated that these skeletal abnormalities are likely a secondary consequence to muscle loss (sarcopenia); however, it remains unclear if they could be due to a direct intrinsic skeletal defect. Recent evidence has emerged implicating adult stem cell dysfunction in the histopathogenesis of DMD. Muscle derived progenitor cells (MPCs) isolated from dystrophin/utrophin double knock-out (dKO) mice (a severe animal model of DMD) have been found to be defective in their proliferation and differentiation capacities. We, and others, have reported that these dKO mice exhibit a spectrum of degenerative changes in their bone, articular cartilage, and intervertebral discs and experience spinal deformities, heterotopic ossification, cardiomyopathy and a decreased lifespan, all of which support a premature musculoskeletal aging phenotype in this mouse model. A defect in bone healing was also observed in these mice; however, it is still unclear whether this defect is an intrinsic bone healing problem or associated with the secondary effects of sarcopenia (Aim 1). Preliminary evidence supports the existence of an adult stem cell defect in both MPCs and mesenchymal stem cells (MSCs) in these mice, supporting the theory that abnormal bone healing could be the consequence of an autonomous defect in the adult stem cell compartment. Thus the second aim of this project will be to further validate whether the MPCs and MSCs in these mice, analyzed at different ages, are defective in their proliferation and osteogenic differentiation capacities compared to MPCs and MSCs isolated from mdx and wild type (WT) mice. It has recently been shown that reducing fibroblast growth factor-2 (FGF2) activity prevents stem cell depletion/exhaustion; therefore, we also propose to determine whether FGF2 inhibitor-loaded biomimetic coacervate could rescue this autonomous adult stem cell defect and delay the onset of bone related histopathologies in dKO mice (Aim 2). Since there is also evidence that the stem cell niche may also negatively impact adult stem cell function, via a non-autonomous mechanism, we propose experiments to determine if the bone defect observed in dKO mice can be rescued through parabiotic pairing which will rejuvenate the dystrophic microenvironment by creating a shared circulation between a dKO and a young WT animal (Aim 3). We have preliminary data that supports the fact that circulating factors from young animals have a beneficial effect on the bone morphologies and healing capacity of dKO mice. In summary, this innovative grant application will: 1) determine whether the bone abnormalities and healing in dKO mice represent an intrinsic bone defect and 2) characterize whether the progressive bone histopathology observed in the dKO mice, is primarily driven by cell autonomous and/or non-autonomous mechanisms.

描述（由申请人提供）：杜氏肌营养不良症（DMD）是一种退行性肌肉疾病，其特征是肌营养不良蛋白表达缺乏，最终导致心脏或呼吸衰竭。 DMD 患者还会出现骨质减少、脆性骨折和脊柱侧凸，这表明 DMD 患者也存在骨骼系统稳态缺陷。据推测，这些骨骼异常可能是肌肉损失（肌肉减少症）的继发后果；然而，目前尚不清楚它们是否可能是由于直接内在原因造成的 骨骼缺陷。最近的证据表明 DMD 的组织病理发生中存在成体干细胞功能障碍。从肌营养不良蛋白/肌营养不良蛋白双敲除 (dKO) 小鼠（DMD 的一种严重动物模型）中分离出的肌肉来源的祖细胞 (MPC) 被发现在增殖和分化能力方面存在缺陷。我们和其他人报告说，这些 dKO 小鼠的骨骼、关节软骨和椎间盘表现出一系列退行性变化，并经历脊柱畸形、异位骨化、心肌病和寿命缩短，所有这些都支持肌肉骨骼过早衰老的表型在这个鼠标模型中。在这些小鼠中还观察到骨愈合缺陷；然而，目前尚不清楚这种缺陷是否是一种内在的骨愈合问题或与肌肉减少症的继发影响有关（目标 1）。初步证据支持这些小鼠的 MPC 和间充质干细胞 (MSC) 中都存在成体干细胞缺陷，这支持了以下理论：骨愈合异常可能是成体干细胞区室自主缺陷的结果。因此，该项目的第二个目标是进一步验证在不同年龄进行分析的这些小鼠中的 MPC 和 MSC 与从 mdx 和野生型 (WT) 小鼠中分离的 MPC 和 MSC 相比，其增殖和成骨分化能力是否存在缺陷。 。最近的研究表明，降低成纤维细胞生长因子 2 (FGF2) 活性可防止干细胞耗竭/耗尽；因此，我们还建议确定负载 FGF2 抑制剂的仿生凝聚层是否可以挽救这种自主成体干细胞缺陷并延迟 dKO 小鼠骨相关组织病理学的发生（目标 2）。由于还有证据表明干细胞生态位也可能通过非自主机制对成体干细胞功能产生负面影响，因此我们提出实验来确定 dKO 小鼠中观察到的骨缺损是否可以通过共生配对来挽救，这将使营养不良的小鼠恢复活力。通过在 dKO 和幼年 WT 动物之间创建共享循环的微环境（目​​标 3）。我们有初步数据支持这样一个事实：幼年动物的循环因子对 dKO 小鼠的骨形态和愈合能力有有益的影响。总之，这项创新的拨款申请将：1）确定 dKO 小鼠的骨异常和愈合是否代表内在的骨缺陷，2）表征在 dKO 小鼠中观察到的进行性骨组织病理学是否主要由细胞自主和/或非自主机制。