Silva Haroldo, Conboy Irina M
Department of Bioengineering, University of California, Berkeley, California 94720, USA
Adult or organ stem cells present in mammalian organ systems are essential for the maintenance and repair of these organs throughout adult life. This key function of adult stem cells requires precise coordination of highly regulated molecular signaling to ensure proper cellular, tissue, and organ homeostasis. Such coordination deteriorates with age and consequentially, adult stem cells in the aged organism do not regenerate tissue damaged by stress, injury or attrition as efficiently as in the young. The molecular mechanisms associated with deficits in organ stem cell function with advancing age are for the most part unknown. Nonetheless, recent studies are beginning to shed light on the processes involved in stem cell aging, particularly in adult skeletal muscle stem cells, namely satellite cells. In this chapter, the current mechanisms believed to contribute to stem cell aging are reviewed, focusing on satellite cells and comparing them to hematopoietic stem cells as these cell types offer interesting perspectives regarding extrinsic versus intrinsic aging programs. Undoubtedly, knowledge of how organ stem cells change with advancing age will help in understanding the aging process itself and might provide novel therapeutic venues for the enhancement of tissue regeneration.
哺乳动物器官系统中存在的成体干细胞或器官干细胞对于成年期这些器官的维持和修复至关重要。成体干细胞的这一关键功能需要高度调控的分子信号精确协调，以确保细胞、组织和器官的适当稳态。随着年龄增长，这种协调会恶化，因此，衰老生物体中的成体干细胞不像年轻生物体中的干细胞那样有效地再生因应激、损伤或磨损而受损的组织。与器官干细胞功能随年龄增长而出现缺陷相关的分子机制在很大程度上尚不清楚。尽管如此，最近的研究开始揭示干细胞衰老所涉及的过程，特别是在成体骨骼肌干细胞，即卫星细胞中。在本章中，我们将回顾目前认为导致干细胞衰老的机制，重点关注卫星细胞，并将它们与造血干细胞进行比较，因为这些细胞类型为外在与内在衰老程序提供了有趣的视角。毫无疑问，了解器官干细胞如何随着年龄增长而变化将有助于理解衰老过程本身，并可能为增强组织再生提供新的治疗途径。
