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BioMed Research International
Volume 2014 (2014), Article ID 560629, 9 pages
http://dx.doi.org/10.1155/2014/560629
Review Article

Macrophage Plasticity in Skeletal Muscle Repair

1Division of Regenerative Medicine, Stem Cells and Gene Therapy, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milano, Italy
2San Raffaele University, Via Olgettina 58, 20132 Milano, Italy
3Department of Health Sciences, University of Milano-Bicocca, via Cadore 48, 20900 Monza, Italy

Received 18 January 2014; Revised 13 March 2014; Accepted 31 March 2014; Published 17 April 2014

Academic Editor: Pura Muñoz-Cánoves

Copyright © 2014 Elena Rigamonti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Macrophages are one of the first barriers of host defence against pathogens. Beyond their role in innate immunity, macrophages play increasingly defined roles in orchestrating the healing of various injured tissues. Perturbations of macrophage function and/or activation may result in impaired regeneration and fibrosis deposition as described in several chronic pathological diseases. Heterogeneity and plasticity have been demonstrated to be hallmarks of macrophages. In response to environmental cues they display a proinflammatory (M1) or an alternative anti-inflammatory (M2) phenotype. A lot of evidence demonstrated that after acute injury M1 macrophages infiltrate early to promote the clearance of necrotic debris, whereas M2 macrophages appear later to sustain tissue healing. Whether the sequential presence of two different macrophage populations results from a dynamic shift in macrophage polarization or from the recruitment of new circulating monocytes is a subject of ongoing debate. In this paper, we discuss the current available information about the role that different phenotypes of macrophages plays after injury and during the remodelling phase in different tissue types, with particular attention to the skeletal muscle.