Aging and stem cell renewal

Abstract

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.