SKELETAL MUSCLE STEM CELLS FOR TISSUE REPAIR

描述（由申请人提供）：颅面修复面临的一个主要问题是，对于包括半面小畸形、单侧唇腭裂以及TMJ缺陷在内的畸形患者，难以恢复软组织功能和轮廓。特别是骨骼肌缺损的修复由于其移植和存活困难而受到限制。一种合理的方法是利用现有的肌肉卫星细胞群，这些细胞是在成熟肌肉纤维的基底膜下发现的静止的未分化的前体。损伤后，激活的卫星细胞在启动分化程序后，沿着富含层粘连蛋白的基底膜迁移，增殖、分化并与先前存在的肌纤维结合，从而再生肌肉。最近的证据支持卫星细胞是异质的并且具有干细胞潜能的观点。我们已经证明，层粘连蛋白结合的α - 7整合素对成肌细胞迁移很重要，它在卫星细胞的一个亚群上表达，并在终末分化的肌管中上调。在这个应用中，我们建议研究使用α 7阳性人类卫星细胞直接修复肌肉缺陷的潜力。我们将探索表达α 7的卫星细胞是能够再生骨骼肌和其他组织（如骨）的多能干细胞的假设。这项提议有三个目的。在目标1中，我们将表征人类肌肉来源的卫星细胞，并将α 7整合素的表达与骨骼肌和其他组织谱系的分化潜力联系起来。目的2将确定α 7整合素在人类骨骼肌发育过程中的表达和功能。Aim 3的重点是使用表达α 7的人类骨骼肌干细胞来设计体外三维骨骼肌肌纤维。这些研究将为利用成人骨骼肌干细胞对再生肌管进行机械重新整合以修复口面部肌肉结构的策略奠定基础。

DESCRIPTION (provided by applicant): A major problem confronting craniofacial repair is the difficulty in restoring soft-tissue function and contour in patients with anomalies including hemifacial microsomia, unilateral clefts of lips and palate as well as defects in the TMJ. In particular, repair of skeletal muscle defects is limited by difficulty in its transplantation and survival. A logical approach is to use existing population of muscle satellite cells which are quiescent undifferentiated precursors found beneath the basement membrane of mature muscle fibers. Following injury, activated satellite cells regenerate muscle after initiating a differentiation program whereby they migrate along laminin-rich basement membrane, proliferate, differentiate, and integrate with preexisting myofibers. Recent evidence supports the notion that satellite cells are heterogeneous and have stem cell potential. We have shown that the laminin-binding alpha 7 integrin, which is important for myoblast migration, is expressed on a subset of satellite cells and is upregulated in terminally differentiated myotubes. In this application, we propose to examine the potential of using alpha 7-positive human satellite cells for direct repair of muscle defects. We will explore the hypothesis that alpha 7 expressing satellite cells are pluripotent stem cells capable of regenerating skeletal muscle and other tissue such as bone. The proposal represents three aims. In aim 1 we will characterize human muscle-derived satellite cells and correlate expression of alpha 7 integrin with their differentiation potential for skeletal muscle and other tissue lineages. Aim 2 will determine the expression and function of the alpha 7 integrin during human skeletal muscle development. Aim 3 is focused on the use of alpha 7-expressing human skeletal muscle stem cells to engineer in vitro three-dimensional skeletal muscle myofibers. These studies will form the basis for strategies that target the mechanical reintegration of regenerating myotubes to repair orofacial muscle structures using adult skeletal muscle stem cells.