Inducing Skeletal Repair by Mechanical Stimulation

机械线索在关节软骨的发育和维持中起着至关重要的作用 骨骼修复。确定力学环境与关键细胞和分子之间的关系 参与软骨形成的事件直接应用于开发新的、再生的方法 关节软骨修复，产生具有必要机械功能的组织。然而，这些 人们对人际关系的理解还不够深入。这项研究的长期目标是定义细胞、分子 以及参与透明软骨出生后发育的机械调节过程。朝向这个方向 最后，我们建立了一种活体大鼠骨骼修复模型，在该模型中，每天应用循环弯曲运动 至骨干中部截骨间隙可在间隙内及周围形成强健的软骨组织。 重要的是，这种新生成的软骨具有许多透明软骨的特征，而不是 通常在骨修复过程中形成的纤维软骨。这里提出的工作的假设是 功能性透明软骨可以通过机械调节的骨骼修复过程在出生后形成。 提出了三个具体目标。目标#1将描述新生成的TRIE的机械功能 软骨。将使用纳米压痕、渗透负荷和生化分析来比较两相 新生软骨的材料特性、肿胀行为和固定电荷密度 天然关节软骨。目标2将定义基因表达和组织的时空模式 用原位杂交、免疫组织化学和免疫组织化学方法研究机械刺激诱导的结构 组织形态计量学。目标#3将定义在机械加工过程中产生的局部机械环境 通过使用实验确定的组织材料特性的有限元分析进行刺激 几何图形作为输入。将对有限元结果进行实验验证。集成 AIMS#2和AIMS#3的结果将允许直接评估局部机械提示之间的一致性 以及细胞和分子反应。集体发现将反过来确定候选路径，这些路径可以 成为未来关节软骨修复和再生研究的靶点。这些加在一起， 实验是确定出生后涉及的机械调节过程的第一步 功能性透明软骨的形成。

Mechanical cues play a critical role in the development and maintenance of articular cartilage as well as in skeletal repair. Defining relationships between the mechanical environment and key cell and molecular events involved in cartilage formation has direct application in developing novel, regenerative approaches to articular cartilage repair that produce tissue with the requisite mechanical function. However, these relationships are not well understood. The long term goal of this research is to define the cellular, molecular and mechano-regulatory processes involved in the postnatal development of hyaline cartilage. Toward this end, we have developed an in vivo rat model of skeletal repair in which a cyclic bending motion applied daily to a mid-diaphyseal osteotomy gap results in robust cartilage formation within and surrounding the gap. Importantly, this newly generated cartilage has many characteristics of hyaline cartilage, as opposed to the fibrous cartilage typically formed during bone repair. The hypothesis of the work proposed here is that functional hyaline cartilage can be formed postnatally via mechano-regulated skeletal repair processes. Three specific aims are proposed. Aim #1 will characterize the mechanical function of trie newly generated cartilage. Nanoindentation, osmotic loading, and biochemical assays will be used to compare the biphasic material properties, swelling behavior, and fixed charge density of the newly generated cartilage to those of native articular cartilage. Aim #2 will define the spatiotemporal patterns of gene expression and tissue structure induced by the mechanical stimulation using in situ hybridization, immunohistochemistry and histomorphometry. Aim #3 will define the local mechanical environment induced during the mechanical stimulation via finite element analyses that use experimentally determined tissue material properties and geometry as input. Experimental validation of the finite element results will be performed. Integration of results from Aims #2 and #3 will allow direct assessment of correspondence between local mechanical cues and cell and molecular responses. The collective findings will in turn identify candidate pathways that can be targeted in future studies of articular cartilage repair and regeneration. Taken together, these experiments represent the first steps in defining the mechano-regulated processes involved in the postnatal formation of functional hyaline cartilage.