Monocyte/macrophage interactions with myogenic precursor cells during skeletal muscle regeneration

Abstract

Adult skeletal muscle has the remarkable property of regenerating after damage, owing to satellite cells and myogenic precursor cells becoming committed to adult myogenesis to rebuild the muscle. This process is accompanied by the continuing presence of macrophages, from the phagocytosis of damaged myofibres to the full re‐formation of new myofibres. In recent years, there has been huge progress in our understanding of the roles of macrophages during skeletal muscle regeneration, notably concerning their effects on myogenic precursor cells. Here, we review the most recent knowledge acquired on monocyte entry into damaged muscle, the various macrophage subpopulations, and their respective roles during the sequential phases of muscle repair. We also discuss the role of macrophages after exercise‐induced muscle damage, notably in humans.

Highly Dynamic Transcriptional Signature of Distinct Macrophage Subsets during Sterile Inflammation, Resolution, and Tissue Repair

“…1) and global gene expression analysis was performed. Because normal skeletal muscle parenchyma contains only few macrophages (12,19), this state was not evaluated. Notably, with very few amounts of Ly6C pos cells being recovered at day 8, only one point (and not triplicate) was analyzed, to avoid unethical sacrifice of numerous mice.…”

Recovery of Skeletal Striated Muscle Tissue in a Model of Reversible Injury

“…Saclier et al used the term regenerated myofiber, to refer to the myocytes with central nuclei [36]. The presence of central nuclei indicates a stage of differentiation and recovery in the striated skeletal muscle tissue underwent to injury [35,36]. In the present research, the soleus and the extensor carpi radialis longus evidenced different patterns of regeneration for each muscle.…”

“…Itoh et al evidenced central nuclei in the tibialis anterior that was underwent to one hour of ischemia with a gradual decreasing until day 14 of reperfusion [35]. Saclier et al used the term regenerated myofiber, to refer to the myocytes with central nuclei [36]. The presence of central nuclei indicates a stage of differentiation and recovery in the striated skeletal muscle tissue underwent to injury [35,36].…”

Myeloid HIFs Are Dispensable for Resolution of Inflammation during Skeletal Muscle Regeneration

“…MPs are essential for skeletal muscle regeneration (22,23). Effectively, when the recruitment of circulating monocytes is totally prevented during the first 24 h after injury, muscle regeneration is totally inhibited, with the persistence of necrotic fibers until 7 d after injury (22).…”

“…Effectively, when the recruitment of circulating monocytes is totally prevented during the first 24 h after injury, muscle regeneration is totally inhibited, with the persistence of necrotic fibers until 7 d after injury (22). Moreover, a series of works using mice deficient for either the chemokine receptor CCR2 or its main ligand CCL2/ MCP1 shows impaired muscle regeneration characterized by formation of fat, decrease in the diameter of new myofibers, and reduced capillary number (23). This was associated with a dramatic decrease of MP infiltration in muscle (24)(25)(26).…”