Regulation of adult stem cells in skeletal muscle hypertrophy and regeneration -Application to sports sciences-

众所周知，骨骼肌在响应载荷和应力时表现出很大的可塑性。然而，肌肉可塑性的分子机制尚不清楚。建立肌肉可塑性的分子机制，对预防肌肉萎缩、诱导运动员及患者康复过程中的肌肉肥大、促进损伤骨骼肌的恢复都有重要意义。卫星细胞位于骨骼肌细胞基底层，在肌肉肥大、再生和再生长中起重要作用。骨骼肌干细胞，如侧群（SP）细胞，也可能在肌肉可塑性中起部分作用。本研究的目的是建立骨骼肌卫星细胞和干细胞在肌肉可塑性中的作用，并探讨这些细胞的调节因子。在这项研究中，我们建立了机械拉伸在骨髓干细胞和肌肉卫星细胞等多种细胞上的应用方法，以及骨骼肌纤维单细胞培养的方法。本研究的主要结果表明，加热（热应力）和对骨骼肌的机械拉伸刺激了骨骼肌卫星细胞的增殖潜能，骨骼肌卫星细胞在坏死-再生过程中被激活，骨髓干细胞的激活和再生骨骼肌的机械负荷促进了再生过程。这些结果表明，骨骼肌卫星细胞和干细胞的调控因子依赖于受刺激和再生骨骼肌的细胞内信号。证据可能对运动科学和康复医学有用。

It is well known that skeletal muscles have exhibited a large plasticity in response to loading and stress. However, molecular mechanisms responsible for muscle plasticity are still unclear. It is useful for the prevention of muscle atrophy, the induction of muscle hypertrophy not only in athletes, but also in patients during rehabilitation, and the facilitation of the recovery of injured skeletal muscle to establish the molecular mechanisms for muscle plasticity. It has been suggested that satellite cells, located under the basal lamina of skeletal muscle cells, play an important role in muscle hypertrophy, regeneration, and re-growth. Skeletal muscle stem cell, such as side population (SP) cells, may also take a partial role in muscle plasticity. The purpose of this study was to establish the role of skeletal muscle satellite and stem cells in muscle plasticity and to investigate the regulatory factors for these cells. In this study, we have established the methods for the application of mechanical stretch on various cells including bone marrow stem and muscle satellite cells and for the single cells culture for skeletal muscle fibers. The main results in this study showed that heating (heat-stress) as well as mechanical stretch on skeletal muscle stimulated the proliferative potential of skeletal muscle satellite cells, the activation of skeletal muscle satellite cells were observed during necrosis-regeneration process, and the regenerative process was facilitated by the activation of bone marrow stem cells as well as the mechanical loading on the regenerating skeletal muscle. These results suggested that the regulatory factors for skeletal muscle satellite and stem cells were dependent on the intracellular signals in the stimulated and regenerating skeletal muscles. Evidences may be useful for sports sciences as well as rehabilitation medicine.