Mature & Aging Tendons: Extracellular Matrix Interactions in the Injury Response

描述（由申请人提供）：本研究的总体目的是确定核心蛋白聚糖和双糖链蛋白聚糖在成熟肌腱损伤修复反应过程中结构和功能重建中的协调调节作用，并确定衰老对核心蛋白聚糖/双糖链蛋白聚糖介导的肌腱修复调节的影响。肌腱结构-功能关系的分析提供了一个框架，可以定量评估细胞外基质分子的调节作用及其相互作用。我们假设肌腱的损伤反应涉及正常发育顺序的部分重现。这包括双糖链蛋白聚糖和核心蛋白聚糖的差异表达，提供重建结构和功能所需的协调调节相互作用。此外，在衰老过程中，肌腱无法重现正常的 SLRP 表达模式，从而损害结构和功能的重建（即，老化的肌腱将无法忠实地重现正常的差异表达模式）。为了检验这些假设，我们将分析核心蛋白聚糖和双糖链蛋白聚糖表达的变化对成熟、衰老和老年小鼠的指长屈肌 (FDL) 肌腱伤口修复的影响。这些研究将利用我们新型的 FDL 肌腱损伤模型。将使用核心蛋白聚糖缺失、双糖链蛋白聚糖缺失、复合突变体和野生型小鼠来操纵SLRP表达。将使用生物力学、生物化学、免疫化学和结构分析来定量评估机械和组织特性以及基质蛋白和细胞因子的概况，从而提供重要的新数据。具体目标是： 目标 1：确定双糖链蛋白聚糖和核心蛋白聚糖在成熟肌腱、老化肌腱和老年肌腱 FDL 肌腱损伤修复反应过程中对生物力学特性恢复的差异调节功能；目标 2：定义双糖链蛋白聚糖和核心蛋白聚糖的损伤相关表达模式；受伤后肌腱的组织和成分测量；以及核心蛋白聚糖和双糖链蛋白聚糖在成熟、衰老和老年小鼠损伤后肌腱结构重建中的调节作用；目标 3：使用成熟、老化和老年 FDL 肌腱的多元回归分析，确定生物力学特性与响应损伤的组织和成分测量之间的关系。这些分析将为核心蛋白聚糖和双糖链在损伤修复反应中的调节作用提供基本的了解。此外，我们将定义一个涉及成熟、老化和老化肌腱中这些 SLRP 相互作用的定量结构功能模型。这些信息不仅将阐明导致这些变化的机制，而且还将提供一个框架，用于进一步研究这些 SLRP 的对比和潜在补偿作用，这可能有助于设计改进的肌腱损伤治疗方式。此外，定义功能性肌腱再生中涉及的调节相互作用将为功能性替代物的组织工程奠定基础。公共健康相关性：本申请的重点是阐明涉及特定细胞外基质成分的相互作用在肌腱损伤反应及其随肌腱老化的功能改变中的调节作用。在运动中、工作中或由于衰老过程，肌腱损伤会导致严重的疼痛和残疾，导致巨大的医疗费用、工作损失和生活质量下降。

DESCRIPTION (provided by applicant): The overall aim of this study is to determine the coordinate regulatory role(s) of decorin and biglycan in the re- establishment of structure and function during the repair response to injury in mature tendons and to define the effects of aging on decorin/biglycan mediated regulation of tendon repair. The analysis of tendon structure- function relationships provides a framework where the regulatory roles of extracellular matrix molecules and their interactions can be quantitatively evaluated. We hypothesize that the injury response in tendon involves a partial recapitulation of the normal developmental sequence. This includes the differential expression of biglycan and decorin providing the coordinate regulatory interactions required for re-establishment of structure and function. In addition, during aging, the tendon is unable to recapitulate the normal SLRP expression patterns thereby compromising the re-establishment of structure and function (i.e., the aged tendons will not be able to faithfully recapitulate the normal differential expression pattern). To test these hypotheses, we will analyze the effects of changes in decorin and biglycan expression on repair of flexor digitorum longus (FDL) tendon wounds in mature, aging and aged mice. These studies will utilize our novel injury model of the FDL tendon. SLRP expression will be manipulated using decorin-null, biglycan-null, compound mutant and wild type mice. The mechanical and organizational properties, as well as profiles of matrix proteins and cytokines will be quantitatively evaluated using biomechanical, biochemical, immunochemical and structural analyses, providing significant new data. The specific aims are to: Aim 1: Determine the differential regulatory function(s) of biglycan and decorin on restoration of biomechanical properties during the repair response to FDL tendon injury in mature, aging and aged tendons; Aim 2: Define injury-associated expression patterns of biglycan and decorin; organizational and compositional measures of tendons after injury; and the regulatory roles of decorin and biglycan in re-establishment of tendon structure after injury in mature, aging and aged mice; Aim 3: Identify relationships between biomechanical properties and organizational and compositional measures in response to injury using multiple regression analyses in mature, aging and aged FDL tendons. These analyses will provide a fundamental understanding of the regulatory roles of decorin and bigylcan in the repair response to injury. In addition, we will define a quantitative structure-function model of interactions involving these SLRPs in mature, aging and aged tendons. This information will not only elucidate mechanisms responsible for the changes, but will also provide a framework for further investigation into the contrasting and potentially compensatory roles of these SLRPs that may aid in the design of improved treatment modalities for tendon injuries. In addition, defining the regulatory interactions involved in the regeneration of a functional tendon will provide a foundation for the tissue engineering of functional replacements. PUBLIC HEALTH RELEVANCE: The focus of this application is to elucidate the regulatory role(s) of interactions involving specific extracellular matrix components in the response to tendon injury as well as in their functional alterations with tendon aging. In sports, at work, or due to aging processes, tendon injuries cause significant pain and disability, resulting in enormous healthcare costs, loss of work, and a decrease in the quality of life.