Skeletal muscle fibrosis: an overview

Extracellular matrix (ECM) is an essential component of skeletal muscle. It provides a framework structure that holds myofibers and blood capillaries and nerves supplying the muscle. In addition, it has a principal role in force transmission, maintenance and repair of muscle fibers. Excessive accumulation of ECM components, especially collagens, either due to excessive ECM production, alteration in ECM-degrading activities, or a combination of both is defined as fibrosis. Skeletal muscle fibrosis impairs muscle function, negatively affects muscle regeneration after injury and increases muscle susceptibility to re-injury, therefore, it is considered a major cause of muscle weakness. Fibrosis of skeletal muscle is a hallmark of muscular dystrophies, aging and severe muscle injuries. Thus, a better understanding of the mechanisms of muscle fibrosis will help to advance our knowledge of the events that occur in dystrophic muscle diseases and develop innovative anti-fibrotic therapies to reverse fibrosis in such pathologic conditions. This paper explores an overview of the process of muscle fibrosis, as well as different murine models for studying fibrosis in skeletal muscles. In addition, factors regulating fibrosis and strategies to inhibit muscle fibrosis are discussed.