Soluble Motogens and Chemoattractants from Damaged Muscle

描述（由申请人提供）：骨骼肌不仅提供运动所需的收缩力，还提供维持姿势和呼吸所需的收缩力。因此，削弱或损害骨骼肌的疾病不仅会降低生活质量，而且在杜氏肌营养不良症等病例中是致命的。分化的肌肉细胞处于有丝分裂末期，不能产生新的肌核来替代因损伤或疾病而丢失的肌核；一种被称为卫星细胞的成体干细胞群体为肌肉肥大、修复和再生提供新的承诺肌肉细胞。卫星细胞分布在整个肌肉中，如果它们在肌肉受损区域内，它们将从通常的静止状态激活并增殖形成一个替代成肌细胞池，这些成肌细胞将分化成新的肌纤维或与受损的肌纤维融合，以快速有效地修复肌肉损伤。一个越来越令人感兴趣的领域是损伤区域远端的卫星细胞通过细胞迁移被招募和重新安置的可能性；这将提高卫星细胞介导的肌肉再生效率。将卫星细胞注射到营养不良肌肉中的治疗性移植研究几乎没有取得成功，其中一个原因是注射的细胞无法扩散和有效地移植。我们提出的实验将探索受损肌肉释放的因子促进卫星细胞的一般运动或刺激卫星细胞归巢到特定区域的能力；这些研究对于确定需要在以后的建议中进一步深入研究的因素的数量和性质是必要的。因此，了解卫星细胞在体内移动和重新定位的能力，以及这两种活动在肌肉再生中所起的作用，不仅会增加对肌肉再生的基本了解，而且会影响DMD和其他肌肉疾病的临床治疗。在这些实验过程中，我们也在与Kanappan Palaniappan博士合作，致力于改进培养细胞自动跟踪的方法。我们将产生一个极其庞大的跟踪细胞数据集，这对于开发能够复制人类研究人员所做的跟踪选择的算法是必要的。鉴于多种环境下视频数据的急剧增加，以及对细胞运动的兴趣，在这个和其他系统中，能够准确检测和跟踪复杂、高背景环境中位置变化的软件工具将对许多从事干细胞、发育和细胞生物学工作的团队有用。

DESCRIPTION (provided by applicant): Skeletal muscle provides the contractile force necessary for not only locomotion but also maintenance of posture and respiration. Diseases that weaken or damage skeletal muscle therefore decrease not only quality of life but are, in cases such as Duchenne's muscular dystrophy, fatal. Differentiated muscle cells are terminally postmitotic and cannot generate new myonuclei to replace those lost to damage or disease; a population of adult stem cells termed satellite cells serves to supply new committed muscle cells for muscle hypertrophy, repair, and regeneration. Satellite cells are distributed throughout the muscle and it is well- established that if they are within an area of muscle that is damaged they will activate from their usual quiescent state and proliferate to form a pool of replacement myoblasts, which will differentiate into new muscle fibers or fuse with damaged ones to rapidly and effectively repair the muscle damage. An area of increasing interest is the potential for satellite cells distal to an area of damage to be recruited and relocated through cell migration; this would enhance the efficiency of satellite cell-mediated muscle regeneration. Therapeutic engraftments studies in which satellite cells are injected into dystrophic muscle have met with little success, and one reason has been a failure of injected cells to spread and efficiently engraft. The experiments we propose will explore the ability of factors released by damaged muscle either to promote general motility of satellite cells or to stimulate homing of satellite cels to a specific area; these studies are necessary to define the number and nature of the factors that would require further in-depth study in a later proposal. An understanding of the capacity of satellite cells to move and relocate in vivo, and the role those two activities play in muscle regeneration, would therefore add not only to basic understanding of muscle regeneration but also impact clinical therapies for DMD and other muscle diseases. In the course of these experiments, we are also working towards improved methods for automated tracking of cells in culture, in collaboration with Dr. Kanappan Palaniappan. We will produce an extremely large dataset of tracked cells, which is necessary to develop algorithms capable of replicating tracking choices made by a human researcher. Given the dramatic increase in both video data in multiple contexts and interest in cell motility in this and other systems, software tools that can accurately detect and track changes in position in a complex, high-background environment will be useful to many groups working in stem cells, development, and cell biology.