SKELETAL MUSCLE STEM CELLS FOR TISSUE REPAIR

描述(申请人提供)：颅面修复面临的一个主要问题是难以恢复畸形患者的软组织功能和轮廓，包括半面部巨大症、单侧唇腭裂以及TMJ缺陷。特别是，骨骼肌缺陷的修复受到移植和存活困难的限制。一个合乎逻辑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前体细胞。损伤后，激活的卫星细胞在启动分化程序后再生肌肉，从而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整合。最近的证据支持这样的观点，即卫星细胞是异质的，具有干细胞潜力。我们已经证明，层粘连蛋白结合的α7整合素对成肌细胞的迁移是重要的，它表达在卫星细胞的一个子集上，并在终末分化的肌管中上调。在这一应用中，我们建议研究使用阿尔法7阳性的人类卫星细胞直接修复肌肉缺陷的可能性。我们将探索一种假设，即表达阿尔法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。该提案代表了三个目标。在目标1中，我们将表征人类肌肉来源的卫星细胞，并将α7整合素的表达与其在骨骼肌和其他组织谱系中的分化潜能相关联。目的2将确定人骨骼肌发育过程中α7整合素的表达和功能。目的3重点是利用表达α7的人骨骼肌干细胞在体外设计三维骨骼肌肌纤维。这些研究将为以再生肌管的机械融合为目标的战略奠定基础，以使用成年骨骼肌干细胞修复口面部肌肉结构。

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.