Yiou René, Lefaucheur Jean-Pascal, Atala Anthony
Laboratory of Tissue Engineering and Cellular Therapeutics, Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
Anat Embryol (Berl). 2003 May;206(6):429-35. doi: 10.1007/s00429-003-0313-x. Epub 2003 May 1.
The regeneration of adult skeletal muscle is mediated by satellite cells. Classically, these are considered to be somitically derived cells that colonize the limbs during early embryogenesis. The striated urethral sphincter presents specific developmental characteristics that distinguish it from skeletal muscles, such as the non-somitic origin of its precursor cells and the late formation of its myofibers. This prompted us to determine whether the striated urethral sphincter can regenerate after injury by the same mechanism as skeletal muscles. By means of the single myofiber explant culture technique we investigated the presence of satellite cells in the striated urethral sphincter of male mice and evaluated their ability to recapitulate a myogenic program. In addition, a myotoxic substance (notexin) was injected into the sphincter in order to provoke rapid destruction of the myofibers; the regeneration process was studied by means of electrophysiological and histological techniques. Satellite cells expressing pax7 were found attached to the sphincteric myofibers. They proliferated and expressed MyoD, Myf5 and desmin after 2 days in culture. After 10 days, they formed multinucleated myotubes expressing alpha-actinin-2. In vivo, complete recovery of the striated urethral sphincter, as assessed by normalization of muscle strength and of myofiber number and diameter, was observed after 3 weeks, and resulted from the fusion of myogenic cells. These results demonstrate that the striated urethral sphincter can regenerate by means of a myogenic program involving intrinsic satellite cells. The therapeutic implications of this knowledge and the possible origin of the sphincteric satellite cells are discussed.
成年骨骼肌的再生由卫星细胞介导。传统上，这些细胞被认为是在胚胎发育早期定殖于四肢的体节衍生细胞。横纹尿道括约肌具有一些特定的发育特征，使其有别于骨骼肌，比如其前体细胞的非体节起源以及肌纤维的较晚形成。这促使我们去确定横纹尿道括约肌在损伤后是否能通过与骨骼肌相同的机制再生。我们借助单根肌纤维外植体培养技术，研究了雄性小鼠横纹尿道括约肌中卫星细胞的存在情况，并评估了它们重现肌源性程序的能力。此外，向括约肌注射一种肌毒性物质（蛇毒磷酸二酯酶），以引发肌纤维的快速破坏；通过电生理和组织学技术研究再生过程。我们发现表达配对盒基因7（Pax7）的卫星细胞附着于括约肌肌纤维。培养2天后，它们开始增殖并表达肌源性决定因子（MyoD）、肌原性因子5（Myf5）和结蛋白。10天后，它们形成了表达α - 辅肌动蛋白 - 2的多核肌管。在体内，3周后观察到横纹尿道括约肌完全恢复，这通过肌肉力量、肌纤维数量和直径的正常化得以评估，且这是肌源性细胞融合的结果。这些结果表明，横纹尿道括约肌可通过涉及内在卫星细胞的肌源性程序实现再生。本文还讨论了这一知识的治疗意义以及括约肌卫星细胞可能的起源。
