Roles of the superficial zone in mature articular cartilage

项目总结/摘要 滑膜关节对于全方位的运动和生活质量至关重要。不幸的是，关节-和关节 特别是软骨-对先天性，损伤和年龄相关疾病非常敏感，导致 退化，反映内在软骨修复能力差。目前的临床干预措施不符合 对关节软骨的广泛需求，在很大程度上是由于缺乏对细胞的关键知识， 控制关节软骨正常功能的机制，如润滑和组织维护 成长中的青少年和年轻人。为了推进这些战略，需要更多的信息， 关节软骨发育和适应/响应环境变化的基本机制， vivo.关节软骨的最表层负责分泌蛋白聚糖（润滑剂）进入关节。 允许无摩擦运动的关节囊。许多研究都把这作为他们的主要目标。 功能和增加润滑已经显示出治疗疾病的希望。该项目将采取更广泛的 一种明确定义这些细胞的独特特征和其他潜在功能的方法， 用于治疗方法。特别是，本研究将集中在浅带细胞的相互作用 与关节软骨细胞相连我的申办者实验室进行的发育研究和我掌握的初步数据 从成年小鼠中收集到的信息提供了强有力的证据，表明浅表区不起祖细胞的作用。 群体的基础关节软骨细胞，而不是表明，表面细胞是独特的， 关节软骨细胞因此，我推测，浅带细胞在关节软骨中保持着明显的结构， 软骨，但它们与底层关节软骨细胞的协调功能促进持续， 关节软骨的功能组织。为了验证这一假设，在目标1中，我将描述 表浅区细胞在生长过程中和对损伤的反应过程中的特性与关节炎相比， 软骨细胞在目标2中，我将直接测试成年动物对浅层细胞的需求。在Aim中 3、探讨关节表面细胞与关节软骨细胞协调功能的机制， 保持成熟的关节软骨结构。我将使用多种分析工具，包括组织形态计量学， 共聚焦成像和纳米级机械测试结合RNA测序和原位 杂交方法条件性小鼠模型，包括我们的转基因Prg 4CreER等位基因靶向浅表区 细胞，将在成年阶段和创伤性损伤（DMM模型）后进行检查， 关节中的机械载荷。拟议的研究将提供有关机制的基本知识， 是表浅区细胞功能和对损伤/改变的机械负荷的反应的基础。的数据和 该项目的见解将被证明是至关重要的设想和测试未来的治疗联合战略， 表面区域细胞，为项目提供广泛的相关性和重要性，并提供一个坚实的平台， 这是为了建立我在生物医学和转化医学研究方面的独立职业生涯。

PROJECT SUMMARY/ABSTRACT Synovial joints are essential for full range of motion and quality of life. Unfortunately, the joints -and articular cartilage in particular- are highly susceptible to congenital-, injury- and age-related diseases that lead to degeneration, a reflection of poor intrinsic cartilage repair capacity. Current clinical interventions do not meet the wide range of demands on articular cartilage due, in large part, to lack of crucial knowledge on the cellular mechanisms that govern normal functions of articular cartilage such as lubrication and tissue maintenance growing adolescents and young adults. In order to advance these strategies, more information is needed on basic mechanisms of articular cartilage development and adaptation/response to environmental changes in vivo. The superficial most layer of articular cartilage is responsible for secreting proteoglycans (lubricants) into the joint capsule that allow for frictionless movement. Many studies have focused on this as their primary function, and increasing lubrication has shown promise for disease treatment. This project will take a broader approach to clearly define unique characteristics and other potential functions for these cells that could be targeted for therapeutic approaches. In particular, this study will focus on interactions of superficial zone cells with underlying articular chondrocytes. Developmental studies by my sponsor's lab and preliminary data I have gathered from adult mice provide strong evidence that the superficial zone does not function as a progenitor population for underlying articular chondrocytes, and instead suggests that superficial cells are unique from articular chondrocytes. Thus, I hypothesize that superficial zone cells are maintained distinctly in articular cartilage, but that their coordinated functions with underlying articular chondrocytes promote sustained, functional organization of articular cartilage. To test this hypothesis, in Aim 1 I will characterize the unique properties of superficial zone cells during growth and during their response to damage compared to articular chondrocytes. In Aim 2, I will directly test the requirement of the superficial zone cells in adult animals. In Aim 3, I will explore mechanisms of coordinated functions between superficial cells and articular chondrocytes to maintain mature articular cartilage structure. I will use multiple analytical tools including histomorphometry, confocal imaging, and nano-scale mechanical testing in combination with RNA sequencing and in situ hybridization. Conditional mouse models, including our transgenic Prg4CreER allele to target superficial zone cells, will be examined at adult stages and following a traumatic injury (DMM-model) that significantly alters mechanical loading in the joint. The proposed studies will provide essential knowledge on mechanisms that underlie superficial zone cell functions and responses to damage/altered mechanical load. The data and insights from the project will prove essential to envision and test future therapeutic joint strategies that target superficial zone cells, providing broad relevance and importance to the project and offering a solid platform on which to establish my independent career in biomedical and translational medicine research.