Revealing muscle stem cell heterogeneity in mice and humans through deep single-cell analysis

项目总结/摘要 肌肉干细胞（Muscle Stem Cells，MuSC），又称卫星细胞，是骨骼肌再生的关键细胞 在生活中。在老年人中，受伤后的肌肉质量和再生能力逐渐下降， 导致生活质量下降。我们最近已经证明，前瞻性分离的MuSC， 老年小鼠是高度异质性的，并且作为一个群体，其再生能力显著降低 相对于年轻的成年MuSC，揭示了老年MuSC中先前未检测到的内在干细胞缺陷。的 衰老MuSC的功能障碍的特征在于从可逆静止到细胞衰老的转变， 通过升高p16 Ink 4a细胞周期抑制剂，以及由异常的细胞自主增殖引起的低效自我更新， p38丝裂原活化蛋白激酶和STAT 3通路的激活。是什么原因导致这些固有的 改变以及如何前瞻性地识别和治疗老年小鼠和人类中功能障碍的MuSC仍然存在 没有答案的问题我们建议将联合收割机高通量深度单细胞RNA测序与不同的 成年小鼠和人类肌肉样本和干细胞群体重建算法，以确定细胞- 明确区分小鼠中健康和患病MuSC的表面抗原谱， 人类衰老我们假设这种方法将能够发现异质表达的MuSC 在新发现的功能层次中区分不同干细胞能力的细胞表面抗原。我们将 前瞻性分离和移植小鼠和人MuSC亚群，并进行有限稀释 移植测定和使用生物工程化培养微环境的自我更新测定。我们将执行 条件性缺失和瞬时敲低研究，以研究所鉴定的抗原是否具有机制性 在体内和体外自我更新功能障碍中的作用。这些拟议的研究将提供一个深入的轮廓， 小鼠和人类衰老中肌肉干细胞和祖细胞的组织细胞图谱， 针对失调干细胞的合理治疗开发，以增强老年人的肌肉修复 创伤后。

PROJECT SUMMARY/ABSTRACT Muscle stem cells (MuSCs), also known as satellite cells, are essential to skeletal muscle regeneration throughout life. In aged individuals, muscle mass and regenerative capacity after injury progressively decline, leading to diminished quality of life. We have recently demonstrated that MuSCs prospectively isolated from aged mice are highly heterogeneous and, as a population, have a marked reduction in regenerative capacity relative to young adult MuSCs, revealing a previously undetected intrinsic stem cell defect in aged MuSCs. The dysfunction of aged MuSCs is characterized by a shift from reversible quiescence to cellular senescence, driven by elevation of the p16Ink4a cell-cycle inhibitor, and inefficient self-renewal, caused by aberrant cell-autonomous activation of the p38 mitogen-activated protein kinase and STAT3 pathways. What causes these inherent alterations and how to prospectively identify and treat dysfunctional MuSCs in aged mice and humans remain unanswered questions. We propose to combine high-throughput deep single-cell RNA-sequencing across varied adult mouse and human muscle samples and stem-cell population reconstruction algorithms to identify cell- surface antigen profiles that unambiguously distinguish between health and diseased MuSCs in mouse and human aging. We hypothesize that this approach will enable discovery of heterogeneously expressed MuSC cell-surface antigens that demark differing stem-cell capacities within a new-found functional hierarchy. We will prospectively isolate and transplant mouse and human MuSCs sub-populations and perform limiting dilution transplantation assays and self-renewal assays using bioengineered culture microenvironments. We will perform conditional deletion and transient knockdown studies to investigate if the identified antigens have mechanistic roles in self-renewal dysfunction in vivo and in vitro. These proposed studies will provide a deeply-profiled organized cellular atlas of muscle stem and progenitor cells in mouse and human aging that should enable rational therapeutic development targeting dysregulated stem cells for enhancing muscle repair in the elderly following trauma.