Myogenic stem cells in extraocular muscles

项目总结 眼外肌是一组高度专门化的控制眼睛的骨骼肌。 动静。它们由头部中胚层发育而来，在分子、解剖学和 在生理上与其他骨骼肌不同。EOMS具有独一无二的特性，即 肌营养不良与肌营养不良蛋白-糖蛋白复合体的损伤有关。在杜兴 肌肉营养不良和这种毁灭性的营养不良蛋白缺乏相关疾病的动物模型中， 与其他肌肉的严重早发或晚发损伤相反，EOMS是幸免于难的。的特定特征 EOMS中的肌祖细胞可能在这些肌肉的优先保护中发挥作用。令人惊讶的是， 成体EOMS中的肌源性干细胞和肌祖细胞知之甚少。的困难在于 分离EOMS以获取原代细胞导致缺乏合适的细胞培养模型 旨在确定支持EOM肌纤维终生维持的细胞特性。 这项应用旨在破译三种细胞类型的细胞和分子特征 与肢体和横隔肌相比，EOMS显示出强劲的生长和更新特性， 这可能有助于使EOMS免于营养不良和年龄相关性萎缩。 这些细胞类型是：a)卫星细胞，传统上被认为是肌源性细胞的主要来源 成人骨骼肌祖细胞；b)间质生肌祖细胞；c)微血管相关 收缩细胞(即周细胞)，可直接与肌纤维融合。建议的研究旨在：1) 卫星细胞和间质内细胞表达成肌特异性标志物的特征 EOMS与肢体和横隔肌的比较：2)比较肌源性干细胞的生长和更新潜力 和EOMS中的祖细胞与肢体和横隔肌；3)调查供者的潜力 EOMS相对于肢体和横隔肌的卫星细胞和周细胞在体内的贡献 肌肉修复。野生型和dystrophin缺失小鼠的细胞，携带各种报告基因(用于追踪 不同的细胞类型及其后代)将在体内和培养中进行研究。预期结果 将有助于更好地理解支持EOM的细胞环境 成人生活中的维持，将提供关于微血管相关角色的新见解 骨骼肌发生中的细胞。EOM肌源性祖细胞的进一步特征对于 开发修复策略来治疗眼外肌疾病。拟议中的研究也将摆脱 关于生肌祖细胞在衰老和肌营养不良蛋白缺乏肌肉中的功能状态的新认识， 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.