Science TM：干细胞使与衰老有关的肌无力的速度放缓

　　在小鼠中的一则新的研究报告指出，用干细胞来增加年轻的肌肉可减缓与年龄老化相关的肌无力的进程。 这些发现可能会导致再生性肌肉疗法的出现，这种疗法也许会对罹患肌营养不良症的病人或是那些虚弱的老年人有帮助。 文章的作者提出，如果科学家们能够发现可刺激肌肉中干细胞的小分子或分子组合（这可能会比将干细胞移植到人体内要更容易些），那么这些分子可被用于增进肌肉修复或减少肌肉丧失。 在成年期，损伤后或疾病后肌肉再生主要是靠卫星细胞，这是一种会分裂并参与修复、重新恢复活力和控制骨骼肌组织的干细胞，它可通过发育成为肌肉细胞而令肌肉生长。

　　Bradley Olwin及其同事在这里利用了干细胞的能力并防止了在幼小的小鼠中某一单一肌肉的与年龄老化有关的消瘦。 在该研究中，研究人员将少数的干细胞移植到肌肉受伤的幼小小鼠体内。 该研究小组在两年后对这些小鼠进行检查时发现，这种手术永久性地改变了移植的细胞，使得它们能够抵抗肌肉中的老化过程。 明确地说，这些移植的细胞能够控制它们所在的肌肉并与肌肉融合以形成新的肌肉纤维。 尽管人们对这一过程的机制还不了解，但这些发现提示，通过模仿这些移植的干细胞的功效，科学家们也许能够防止肌肉功能和重量的丧失，而这些通常是在人类老化时出现的情况。

　　推荐英文摘要：

　　Sci Transl Med  DOI: 10.1126/scitranslmed.3001081

　　Prevention of Muscle Aging by Myofiber-Associated Satellite Cell Transplantation

　　John K. Hall1,*, Glen B. Banks2, Jeffrey S. Chamberlain2 and Bradley B. Olwin1

　　1Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.

　　2Departments of Neurology, Medicine, and Biochemistry, University of Washington Medical School, Seattle, WA 98195, USA.

　　Skeletal muscle is dynamic, adapting to environmental needs, continuously maintained, and capable of extensive regeneration. These hallmarks diminish with age, resulting in a loss of muscle mass, reduced regenerative capacity, and decreased functionality. Although the mechanisms responsible for this decline are unclear, complex changes within the local and systemic environment that lead to a reduction in regenerative capacity of skeletal muscle stem cells, termed satellite cells, are believed to be responsible. We demonstrate that engraftment of myofiber-associated satellite cells, coupled with an induced muscle injury, markedly alters the environment of young adult host muscle, eliciting a near-lifelong enhancement in muscle mass, stem cell number, and force generation. The abrogation of age-related atrophy appears to arise from an increased regenerative capacity of the donor stem cells, which expand to occupy both myonuclei in myofibers and the satellite cell niche. Further, these cells have extensive self-renewal capabilities, as demonstrated by serial transplantation. These near-lifelong, physiological changes suggest an approach for the amelioration of muscle atrophy and diminished function that arise with aging through myofiber-associated satellite cell transplantation.