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。我们的产品得到R 01 AR 055299的支持 一个研究小组开创了从骨骼肌中提取大量骨骼肌祖细胞的方法， 小鼠和人类多能ES和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，而且还能为卫星细胞隔室接种， 提供长期的再生。在上一个资助期，我们定义了体外的分子特征- 通过比较它们的转录组谱与原代细胞的转录组谱来产生PS细胞衍生的肌源性祖细胞。 骨骼肌原性祖细胞分离在不同的发育阶段。我们的研究结果表明PS细胞- 衍生的成肌祖细胞具有与胚胎/胎儿成肌细胞相似的分子标记。矛盾的 然而，它们在功能上不同于胎儿成肌细胞，因为PS细胞来源的肌原性祖细胞显示出许多 上级肌纤维植入和播种卫星细胞室的能力，对多次再损伤有反应 并有助于长期的再生。这些结果使我们假设暴露于成年宿主 骨骼肌环境可诱导移植细胞的分子变化。我们发现情况就是这样 移植后重新分离的PS细胞来源的单核细胞（MNC）的转录组分析显示， 分子标记从胚胎/胎儿阶段向新生儿/成人阶段转变。在此更新申请中，我们 提出研究，以了解i）相互作用和分子线索所提供的成人生态位，有利于在 PS细胞衍生的肌源性祖细胞的体内成熟，ii）转录后调节在此过程中的作用， 过程，和iii）植入的动力学和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. Supported by R01 AR055299, 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. In the last funding period, we defined the molecular signature of in vitro- generated PS cell-derived myogenic progenitors by comparing their transcriptome profiles to those of primary skeletal myogenic progenitors isolated at different developmental stages. Our findings revealed that PS cell- derived myogenic progenitors possess a molecular signature similar to embryonic/fetal myoblasts. Paradoxically however, they differ functionally from fetal myoblasts, as PS cell-derived myogenic progenitors show much superior myofiber engraftment and ability to seed the satellite cell compartment, 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 PS cell-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 PS cell-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.