Skeletal muscle healing by M1-like macrophages produced by transient expression of exogenous GM-CSF

Stem Cell Research & Therapy

Timothy Jon Koh¹  Daniela Santoro Rosa²  Roberta Sessa Stilhano³  Leonardo Martins⁴  Camila Congentino Gallo⁴  Patrícia Terra Alves⁴  Tâmisa Seeko Bandeira Honda⁴  Sang Won Han⁵ 

[1] Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, USA;Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, São Paulo, Brazil;Department of Physiological Sciences, Faculdade de Ciências Medicas da Santa Casa de São Paulo, São Paulo, Brazil;Interdisciplinary Center for Gene Therapy, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil;Interdisciplinary Center for Gene Therapy, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil;Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Mirassol 207, 04044-010, São Paulo, SP, Brazil;

关键词: Fibrosis;    Skeletal muscle;    Injury;    Myogenesis;    GM-CSF;    Macrophage;    Arteriogenesis;    Contusion;   

DOI  :  10.1186/s13287-020-01992-1

来源: Springer

【 摘 要 】

BackgroundAfter traumatic skeletal muscle injury, muscle healing is often incomplete and produces extensive fibrosis. The sequence of M1 and M2 macrophage accumulation and the duration of each subtype in the injured area may help to direct the relative extent of fibrogenesis and myogenesis during healing. We hypothesized that increasing the number of M1 macrophages early after traumatic muscle injury would produce more cellular and molecular substrates for myogenesis and fewer substrates for fibrosis, leading to better muscle healing.MethodsTo test this hypothesis, we transfected skeletal muscle with a plasmid vector to transiently express GM-CSF shortly after injury to drive the polarization of macrophages towards the M1 subset. C57BL/6 mouse tibialis anterior (TA) muscles were injured by contusion and electroporated with uP-mGM, which is a plasmid vector that transiently expresses GM-CSF. Myogenesis, angiogenesis, and fibrosis were evaluated by histology, immunohistochemistry, and RT-qPCR; subpopulations of macrophages by flow cytometry; and muscle functioning by the maximum running speed on the treadmill and the recovery of muscle mass.ResultsMuscle injury increased the number of local M1-like macrophages and decreased the number of M2-like macrophages on day 4, and uP-mGM treatment enhanced this variation. uP-mGM treatment decreased TGF-β1 protein expression on day 4, and the Sirius Red-positive area decreased from 35.93 ± 15.45% (no treatment) to 2.9% ± 6.5% (p < 0.01) on day 30. uP-mGM electroporation also increased Hgf, Hif1α, and Mtor gene expression; arteriole density; and muscle fiber number during regeneration. The improvement in the quality of the muscle tissue after treatment with uP-mGM affected the increase in the TA muscle mass and the maximum running speed on a treadmill.ConclusionCollectively, our data show that increasing the number of M1-like macrophages immediately after traumatic muscle injury promotes muscle recovery with less fibrosis, and this can be achieved by the transient expression of GM-CSF.

【 授权许可】

CC BY