Mechanical Loading and Bone

机械负载和骨骼

• 批准号: 8312379
• 负责人: Hiroki Yokota
• 金额: $ 33.26万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-30 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8312379
• 关键词: Adverse effects; Animals; Architecture; Biological Assay; Biological Models; Biomedical Engineering; Bone remodeling; C57BL/6 Mouse; Chondrocytes; Collagen; Data; Diaphyses; Distant; Elbow; Electronics; Environment; Fluorescein; Fluorescence Recovery After Photobleaching; Fluorescent Dyes; Frequencies; Gene Expression; Genes; Goals; Immunoblotting; In Situ; In Vitro; Inflammation; Intercellular Fluid; Interferometry; Joints; Knowledge; Lactalbumin; Lateral; Location; Matrix Metalloproteinases; Measures; Mechanical Stimulation; Mechanics; Microscopic; Minerals; Monitor; Mus; Osteoblasts; Osteogenesis; Pattern; Research; Research Personnel; Resolution; Role; Sodium Fluorescein; Stress; Surface; Synovial Membrane; Testing; Therapeutic; Time; Transport Process; articular cartilage; base; bone; bone cell; bone epiphysis; bone loss; bone mass; enzyme activity; fluid flow; in vivo; joint loading; long bone; mRNA Expression; novel; prevent; programs; protein expression; prototype; response; skeletal; ulna

The long-term objective of the proposed studies is to elucidate the mechanism of mechanotransduction in bone. Our present bioengineering-oriented project developed a high-resolution piezoelectric mechanical loader and evaluated the role of mechanical stimulation in bone using cultured osteoblasts. The results reveal that (a) deformation of 3D collagen matrix can induce strain-induced fluid flow; (b) strain-induced fluid flow, and not strain itself, predominantly activates the stress-responsive genes in osteoblasts; and (c) architecture of 3D collagen matrix establishes a pattern of strain-induced fluid flow and molecular transport. Many lines of evidence in animal studies support enhancement of bone remodeling with strain of 1000 - 2000 microstrains. An unclear linkage between our in vitro studies and these animal studies is the role of strain and fluid flow in bone remodeling. In vitro osteoblast cultures including our current studies use 2D substrates or 3D matrices that hardly mimic the strain-induced fluid flow in vivo. This difference between in vitro and in vivo data makes it difficult to evaluate the role of strain and fluid flow in bone remodeling and anti-inflammation. First, microscopic strain in bone might be higher than the macroscopic strain measured with strain gauges. A local microscopic strain higher than 1000 - 2000 microstrains may therefore drive fluid flow in bone. Second, the lacunocanalicular network in bone could amplify strain-induced fluid flow in a loading-frequency dependent fashion. Lastly, interstitial fluid flow in bone might be induced by in situ strain as well as strain in a distant location, such that deformation of relatively soft epiphyses induces fluid flow in cortical bone in diaphyses. This renewal proposal will use mouse ulnae ex vivo as well as mouse in vivo loading to examine the above possible explanations for the data divergence. Specific aims include: (1) fabricating a piezoelectric mechanical loader for ex vivo and in vivo use; (2) quantifying ex vivo macroscopic and microscopic strains using electronic speckle pattern interferometry as well as molecular transport using fluorescence recovery after photobleaching; (3) conducting bone histomorphometry to evaluate ex vivo data; and (4) examining load-driven adverse effects with gene expression and enzyme activities (e.g., matrix metalloproteinases). Mechanical loads will be given in the ulna-loading (axial loading) and elbow-loading (lateral loading) modes. These two modes have been shown to enhance bone remodeling in the diaphysis with different patterns of strain distribution. Successful completion of the proposed renewal proposal will provide basic knowledge about induction of fluid flow in bone and establish a research platform for devising therapeutic strategies for strengthening bone and preventing bone loss.

这项研究的长期目标是阐明机械传导的机制， 骨头我们目前面向生物工程的项目开发了一种高分辨率的压电机械 加载器，并使用培养的成骨细胞评价机械刺激在骨中的作用。结果 揭示了（a）3D胶原基质的变形可以诱导应变诱导流体流动;（B）应变诱导流体流动 流动，而不是应变本身，主要激活成骨细胞中的应激反应基因;以及（c） 3D胶原基质的结构建立了应变诱导的流体流动和分子运输的模式。 动物研究中的许多证据支持在应变为1000 - 10000的情况下骨重建的增强。 2000个微菌株。我们的体外研究和这些动物研究之间的一个不明确的联系是， 骨重建中的应变和流体流动。体外成骨细胞培养，包括我们目前的研究，使用二维 基质或3D矩阵，几乎不能模拟体内应变诱导的流体流动。这种差异在 体外和体内数据使得难以评估应变和流体流动在骨重建中的作用， 抗炎。首先，骨骼中的微观应变可能高于测量的宏观应变 用应变片因此，高于1000 - 2000微应变的局部微观应变可以驱动流体 在骨头里流动。第二，骨中的腔隙性小管网络可以放大应变诱导的流体流动， 加载频率依赖的方式。最后，原位应变可能引起骨间质液流动 以及在远处位置的应变，使得相对软的骨骺的变形引起流体流动， 骨干中的皮质骨。 本更新提案将使用小鼠离体和小鼠体内负载来检查上述 数据分歧的可能解释。具体目标包括：（1）制作压电陶瓷， 用于离体和体内使用的机械加载器;（2）定量离体宏观和微观应变 使用电子散斑干涉测量以及使用荧光恢复的分子传输 光漂白后;（3）进行骨组织形态测量以评估离体数据;和（4）检查 基因表达和酶活性的负荷驱动的不利影响（例如，基质金属蛋白酶）。 机械载荷将以尺骨载荷（轴向载荷）和肘部载荷（横向载荷）模式给出。 这两种模式已被证明可以增强骨干中的骨重建， 应变分布成功完成拟议的更新提案将提供基本知识 关于诱导骨中的液体流动，并建立研究平台， 强化骨骼，防止骨质流失。