Myogenic stem cells in extraocular muscles

项目摘要 眼外肌（extraocular muscle，EOM）是一组高度特化的控制眼球运动的骨骼肌 动作它们从头部中胚层发育而来，在分子上、解剖学上和 在生理上与其他骨骼肌不同。EOM具有独特的质量， 与肌营养不良蛋白-糖蛋白复合物损伤相关的肌营养不良。迪谢内 肌营养不良症和这种破坏性肌营养不良蛋白缺乏相关疾病的动物模型中， 眼外肌得以幸免，与对其他肌肉的严重早发性或迟发性损伤相反。具体特征 眼外肌中的肌源性祖细胞可能在这些肌肉的优先保留中起作用。令人惊奇的是， 对成人眼外肌中的肌源性干细胞和祖细胞知之甚少。的困难 分离用于收获原代细胞的EOM导致缺乏合适的细胞培养模型 目的在于鉴定支持眼外肌肌纤维终生维持的细胞的特性。 本申请提出破译三种细胞类型的细胞和分子特征 与肢体和膈肌相比，在眼外肌中显示出强劲的生长和更新特性， 这可能有助于保护眼外肌免受肌营养不良和年龄相关性萎缩的影响。 这些细胞类型是：a）卫星细胞，其被经典地认为是肌原性细胞的主要来源。 成体骨骼肌中的祖细胞; B）间质性肌源性祖细胞; c）微血管相关的 收缩细胞（即，周细胞），其可直接与肌纤维融合。建议的研究旨在：1） 表征肌细胞特异性标志物在卫星细胞和肌细胞小生境中的细胞表达， 眼外肌与肢体和膈肌; 2）比较肌源性干的生长和更新潜力 3）研究供体的潜力 来自EOM的卫星细胞和周细胞相对于肢体和膈肌有助于体内 肌肉修复来自携带各种报告基因的野生型和肌养蛋白缺失小鼠的细胞（用于追踪 不同的细胞类型和它们的后代）将在体内和培养物中进行研究。预期结果 的拟议研究将有助于更好地了解支持EOM的细胞环境 维持在成年生活中，并将提供新的见解，微血管相关的作用， 骨骼肌发生中的细胞。眼外肌肌源性祖细胞的进一步表征对于 开发治疗眼外肌疾病的修复策略。拟议的研究还将 关于衰老和肌营养不良蛋白缺乏肌肉中肌源性祖细胞功能状态的新认识， 为肌肉康复策略提供重要信息。

PROJECT SUMMARY Extraocular muscles (EOMs) are a group of highly specialized skeletal muscles that control eye movements. They develop from the head mesoderm and are molecularly, anatomically and physiologically distinct from other skeletal muscles. EOMs possess a unique quality of being spared in muscular dystrophies associated with impairments in the dystrophin-glycoprotein complex. In Duchenne muscular dystrophy and in animal models of this devastating dystrophin deficiency-associated disease, EOMs are spared, contrary to the severe early- or late-onset damage to other muscles. Specific traits of myogenic progenitors in EOMs may play a role in the preferential sparing of these muscles. Surprisingly, very little is known about the myogenic stem and progenitor cells in adult EOMs. The difficulty in isolating EOMs for harvesting primary cells has resulted in the lack of appropriate cell culture models aimed at identifying the properties of cells that support EOM myofiber maintenance through life. This application proposes to decipher cellular and molecular characteristics of three cell types that display robust growth and renewal properties in EOMs compared to limb and diaphragm muscles, a distinction that may contribute to the sparing of EOMs from dystrophinopathy and age-linked atrophy. These cell types are: a) satellite cells, which are classically recognized as the main source of myogenic progenitors in adult skeletal muscle; b) interstitial myogenic progenitors; c) microvascular-associated contractile cells (i.e., pericytes), which may fuse directly with myofibers. The proposed studies aim to: 1) characterize myogenic-specific marker expression by cells in the satellite cell and interstitium niches of EOMs versus limb and diaphragm muscles; 2) compare growth and renewal potential of myogenic stem and progenitor cells in EOMs versus limb and diaphragm muscles; 3) investigate the potential of donor satellite cells and pericytes from EOMs versus limb and diaphragm muscles to contribute to in vivo muscle repair. Cells from wildtype and dystrophin-null mice that carry various reporter genes (for tracing the different cell types and their progeny) will be investigated in vivo and in culture. The expected results of the proposed studies will contribute to a better understanding of the cellular milieu that supports EOM maintenance in adult life and will provide new insights regarding the role of microvasculature-associated cells in skeletal myogenesis. Further characterization of EOM myogenic progenitors is essential for developing repair strategies to treat extraocular muscle disorders. The proposed studies will also shed new light on the functional status of myogenic progenitors in aging and dystrophin-deficient muscles, providing important information for muscle rehabilitation strategies.