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

众所周知，骨骼肌在负荷和压力下表现出很大的可塑性。然而，肌肉可塑性的分子机制仍不清楚。它有助于预防肌肉萎缩，不仅对运动员，而且对康复过程中的患者都有诱导肌肉肥大的作用，并有助于促进受损骨骼肌的恢复，以建立肌肉可塑性的分子机制。有研究表明，位于骨骼肌细胞基底板下的卫星细胞在肌肉肥大、再生和再生长中发挥着重要作用。骨骼肌干细胞，如侧群(SP)细胞，也可能在肌肉可塑性中发挥部分作用。本研究的目的是确定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控因素。在本研究中，我们建立了包括骨髓干细胞和肌肉卫星细胞在内的各种细胞的机械拉伸应用方法，以及骨骼肌纤维的单细胞培养方法。本研究的主要结果表明，骨骼肌加热(热应激)和机械拉伸刺激了骨骼肌卫星细胞的增殖能力，在坏死-再生过程中观察到了骨骼肌卫星细胞的激活，并通过骨髓干细胞的激活和再生骨骼肌上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刺激和再生骨骼肌中的细胞内信号。这些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.