Dual and Beneficial Roles of Macrophages During Skeletal Muscle Regeneration

Abstract

Macrophages are necessary for skeletal muscle regeneration after injury. Muscle recruits inflammatory monocytes/macrophages that switch toward an anti-inflammatory profile upon phagocytosis of debris. In vitro, proinflammatory macrophages stimulate myoblast proliferation, whereas anti-inflammatory macrophages stimulate their differentiation. Thus, macrophages are involved in both phases of skeletal muscle regeneration: first, inflammation and cleansing of necrosis, and then myogenic differentiation and tissue repair.

CD8 T Cells Are Involved in Skeletal Muscle Regeneration through Facilitating MCP-1 Secretion and Gr1high Macrophage Infiltration

“…4H). It might be related to the fact that MPs could influence satellite cells through secretion of diverse growth factors and cytokines (28,42). Previous study has shown that conditioned medium from human MOs/MPs promotes human MPC proliferation by soluble factors, and MOs/MPs facilitate MPC survival by direct contacts (42).…”

“…As an important part of the inflammatory microenvironment, MP plays a key role in muscle regeneration, and its function has been widely recognized. In vivo, the suppression of MPs infiltration leads to incomplete skeletal muscle regeneration and causes adipogenesis and fibrosis (27), whereas depletion of the MPs also reduces the diameter of regenerating myofibers (28). In acute skeletal muscle injury, the function of MPs is important.…”

Role of proinflammatory cytokines and growth factors in skeletal muscle regeneration

“…Makrofagi można podzielić na dwie odrębne populacje (7). Wcześnie pojawiające się komórki, wykazujące ekspresję markera powierzchniowego CD68 i brak ekspresji markera CD163, osiągają najwyższe stęże-nie 24 godziny po uszkodzeniu, a następnie ich liczba gwałtownie spada.…”

Development of a transendothelial shuttle by macrophage modification

“…Ethical complexities aside, this problem may be overcome by identification of the essential bacterial component, which -if not antigenic or pathogenic -could be administered as co-treatment. A greater issue here is the phenotypic change that IL-10 effects in macrophages, polarizing macrophages toward the alternatively activated (M2) phenotype 79,80 . Although this anti-inflammatory phenotype is desired in terms of resolution of inflammation and wound healing, M2 macrophages do not readily cross endothelial barriers 81 .…”

“…Explanations for this outcome could be insufficient cell maturation to allow a M1 phenotype (also not assessed during pilot) that has been shown to transmigrate in vitro Chazaud et al 2009). Additionally, these unmatured monocytes could be less robust, compared to M1 macrophages, and their exposure to the arrest inducing cocktail could have had adverse effects.…”