Skeletal Muscle Regeneration from Pluripotent Stem Cells

总结 多能干细胞（ES和iPS细胞）具有自我更新和分化成多个谱系的能力 体外这使得这些细胞成为研究早期胚胎发育途径和产生 用于再生医学和疾病研究的特定细胞群。我们的研究小组开创了 从小鼠和人多能ES中获得大量骨骼肌源性祖细胞的方法 iPS细胞在移植到营养不良的小鼠中后，这些祖细胞不仅能够产生新的 功能性肌纤维，但也种子卫星细胞室，从而提供长期再生。与 在NIH的支持下，我们定义了体外产生的PSC衍生的肌源性祖细胞的分子特征， 通过比较它们的转录组谱与在不同温度下分离的原代骨骼肌源性祖细胞的转录组谱， 发育阶段我们的研究结果表明PSC衍生的肌源性祖细胞具有分子生物学特性， 类似于胚胎/胎儿成肌细胞的信号。然而，奇怪的是，它们在功能上与胎儿不同。 成肌细胞，作为PSC衍生的肌源性祖细胞，显示出更上级的肌纤维植入和接种能力， 卫星细胞生态位对多次再损伤作出反应，并有助于长期再生。这些结果导致 我们假设暴露于成年宿主骨骼肌环境可能会诱导分子变化 在移植的细胞中。我们发现这是PSC来源的单核细胞的转录组分析的情况。 移植后重新分离的单个核细胞（MNCs）显示分子标记从胚胎/胎儿向 新生儿/成人阶段。在此更新申请中，我们提出研究以了解i）相互作用， 由成体小生境提供的分子线索，有利于PSC衍生的肌源性 祖细胞，ii）转录后调节在该过程中的作用，以及iii）植入的动力学， 特定供体衍生的亚组分的静止状态。

Summary Pluripotent stem cells (ES and iPS cells) have the ability to self-renew and to differentiate into multiple lineages in vitro. This makes these cells a powerful tool to study early embryonic developmental pathways and to generate specific cell populations for regenerative medicine and disease investigation. Our research group has pioneered methods to derive large quantities of skeletal myogenic progenitor cells from mouse and human pluripotent ES and iPS cells. Upon transplantation into dystrophic mice, these progenitors are not only able to generate new functional myofibers, but also to seed the satellite cell compartment, thus providing long-term regeneration. With prior NIH support, we defined the molecular signature of in vitro-generated PSC-derived myogenic progenitors by comparing their transcriptome profiles to those of primary skeletal myogenic progenitors isolated at different developmental stages. Our findings revealed that PSC-derived myogenic progenitors possess a molecular signature similar to embryonic/fetal myoblasts. Paradoxically however, they differ functionally from fetal myoblasts, as PSC-derived myogenic progenitors show much superior myofiber engraftment and ability to seed the satellite cell niche, respond to multiple re-injuries and contribute to long-term regeneration. These results led us to hypothesize that exposure to the adult host skeletal muscle environment may induce molecular changes in transplanted cells. We found this to be the case as transcriptome analysis of PSC-derived mononuclear cells (MNCs) re-isolated after engraftment revealed a shift in molecular signature from embryonic/fetal towards neonatal/adult stages. In this renewal application we propose studies to understand i) the interaction and molecular cues provided by the adult niche that favor the in vivo maturation of PSC-derived myogenic progenitors, ii) the role of post-transcriptional regulation in this process, and iii) the dynamics of engraftment and the quiescence status of specific donor-derived sub-fractions.