Influence of exercise and aging on extracellular matrix composition in the skeletal muscle stem cell niche

Abstract

Skeletal muscle is endowed with a remarkable capacity for regeneration, primarily due to the reserve pool of muscle resident satellite cells. The satellite cell is the physiologically quiescent muscle stem cell that resides beneath the basal lamina and adjacent to the sarcolemma. The anatomic location of satellite cells is in close proximity to vasculature where they interact with other muscle resident stem/stromal cells (e.g., mesenchymal stem cells and pericytes) through paracrine mechanisms. This mini-review describes the components of the muscle stem cell niche, as well as the influence of exercise and aging on the muscle stem cell niche. Although exercise promotes ECM reorganization and stem cell accumulation, aging is associated with dense ECM deposition and loss of stem cell function resulting in reduced regenerative capacity and strength. An improved understanding of the niche elements will be valuable to inform the development of therapeutic interventions aimed at improving skeletal muscle regeneration and adaptation over the life span.

Keywords: aging; exercise; extracellular matrix; niche; stem cells.

Fig. 1.

Schematic representation of the skeletal muscle stem cell niche (A) and its alteration postexercise (B) and aging (C). Exercise results in increased mesenchymal stem cell (MSC) accumulation and ECM reorganization facilitated by matrix metalloproteinases (MMPs). In contrast, aging is associated with increased ECM deposition and reduced growth factor concentration resulting in stem cell dysfunction. [Modified with permission from Taylor & Francis Ltd. (http://www.tandfonline.com) (78).]