Abstract：
While studies have identified characteristics of quiescent satellite cells, their isolation has been hampered by the fact that the isolation procedures result in the activation of these cells into their rapidly proliferating progeny (myoblasts). Thus, the use of myoblasts for therapeutic (regenerative medicine) or industrial applications (cellular agriculture) has been impeded by the limited proliferative and differentiative capacity of these myogenic progenitors. Here we identify a subpopulation of satellite cells isolated from mouse skeletal muscle using flow cytometry that are highly Pax7-positive, exhibit a very slow proliferation rate (7.7 ± 1.2 days/doubling), and are capable of being maintained in culture for at least three months without a change in phenotype. These cells can be activated from quiescence using a p38 inhibitor or by exposure to freeze-thaw cycles. Once activated, these cells proliferate rapidly (22.7 ± 0.2 hours/doubling), have reduced Pax7 expression (3-fold decrease in Pax7 fluorescence vs. quiescence) and differentiate into myotubes with a high efficiency. Furthermore, these cells withstand freeze-thawing readily without a significant loss of viability (83.1 ± 2.1% live). The results presented here provide researchers with a method to isolate quiescent satellite cells, allowing for more detailed examinations of the factors affecting satellite cell quiescence/activation and providing a cell source that has a unique potential in the regenerative medicine and cellular agriculture fields.
摘要：
虽然研究已经确定了静止卫星细胞的特征，由于分离程序导致这些细胞活化为其快速增殖的后代(成肌细胞)的事实,它们的分离受到阻碍。因此，成肌细胞用于治疗(再生医学)或工业应用(细胞农业)的用途受到这些成肌原祖细胞有限的增殖和分化能力的阻碍。在这里，我们使用流式细胞术鉴定了从小鼠骨骼肌中分离的高Pax7阳性的卫星细胞亚群，表现出非常缓慢的增殖速率（7.7±1.2天/倍增），并且能够在培养物中维持至少三个月而不改变表型。这些细胞可以使用p38抑制剂或通过暴露于冻融循环而从静止状态活化。一旦激活,这些细胞迅速增殖（22.7±0.2小时/倍增），Pax7表达减少（Pax7荧光减少3倍与静止）并高效分化为肌管。此外，这些细胞很容易承受冻融而没有明显的生存力损失（83.1±2.1％活）。这里提出的结果为研究人员提供了一种分离静止卫星细胞的方法，允许对影响卫星细胞静止/激活的因素进行更详细的检查，并提供在再生医学和细胞农业领域具有独特潜力的细胞来源。
