Basic Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Stem Cells. Nov 26, 2021; 13(11): 1762-1782
Published online Nov 26, 2021. doi: 10.4252/wjsc.v13.i11.1762
Exosomes derived from inflammatory myoblasts promote M1 polarization and break the balance of myoblast proliferation/differentiation
Zhi-Wen Luo, Ya-Ying Sun, Jin-Rong Lin, Bei-Jie Qi, Ji-Wu Chen
Zhi-Wen Luo, Ya-Ying Sun, Jin-Rong Lin, Bei-Jie Qi, Department of Sports Medicine, Huashan Hospital, Fudan University, Shanghai 200040, China
Ji-Wu Chen, Department of Sports Medicine, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Author contributions: Chen JW, Luo ZW, and Sun YY designed and performed most of the experiments, analyzed and interpreted the data, and wrote the manuscript; Luo ZW and Lin JR assisted during the acquisition, analysis, and interpretation of data and revised the manuscript; Luo ZW, Qi BJ, and Sun YY assisted with data acquisition and revision of the manuscript; all authors have reviewed and approved the final version of the manuscript; Luo ZW and Sun YY contributed equally to this study.
Supported by National Natural Science Foundation of China, No. 81772419 and No. 81972062.
Institutional animal care and use committee statement: The experiments in this study were approved by Huashan Hospital, Fudan University, No. 20171248A703.
Conflict-of-interest statement: The authors declare that they have no competing interests, and all authors should confirm its accuracy.
Data sharing statement: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
ARRIVE guidelines statement: The authors have read the ARRIVE Guidelines, and the manuscript was prepared and revised according to the ARRIVE Guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Ji-Wu Chen, MD, PhD, Academic Research, Chief Doctor, Professor, Department of Sports Medicine, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. jeevechen@gmail.com
Received: May 1, 2021
Peer-review started: May 1, 2021
First decision: June 16, 2021
Revised: June 28, 2021
Accepted: September 2, 2021
Article in press: September 2, 2021
Published online: November 26, 2021
Processing time: 207 Days and 22.1 Hours
ARTICLE HIGHLIGHTS
Research background

More than half of sports injuries in athletes have been reported to be related to muscle damage. Severely injured muscles are prone to re-injury due to fibrotic scar formation caused by prolonged inflammation. How to regulate inflammation and suppress fibrosis is the focus of promoting muscle healing.

Research motivation

Recent studies have found that myoblasts and macrophages play important roles in the inflammatory phase following muscle injury; however, the crosstalk between these two types of cells in the inflammatory environment, particularly the exosome-related mechanisms, has not been well studied.

Research objectives

This study aimed to evaluate the effects of exosomes from inflammatory C2C12 myoblasts (IF-C2C12-Exos) on macrophage polarization and myoblast proliferation/ differentiation.

Research methods

A model of inflammation was established in vitro by lipopolysaccharide stimulation of myoblasts. Multiple methods were used to isolate and identify the exosomes. Gradient concentrations of IF-C2C12-Exos were added to normal macrophages and myoblasts. PKH67 fluorescence tracing, microscopic morphology, Giemsa staining, immunofluorescence, ELISA assays, flow cytometry, western blot, BrdU test, scratch assay, and CCK-8 assay were conducted to determine the mechanism of IF-C2C12-Exos.

Research results

We found that the PKH-67-marked C2C12-Exos can be endocytosed by both macrophages and myoblasts. IF-C2C12-Exos induced M1 macrophage polarization and suppressed the M2 phenotype in vitro. These exosomes also stimulated the inflammatory reactions of macrophages. Furthermore, we demonstrated that IF-C2C12-Exos disrupted the balance of myoblast proliferation/differentiation, leading to enhanced proliferation and suppressed fibrogenic/myogenic differentiation.

Research conclusions

IF-C2C12-Exos can induce M1 polarization, resulting in a sustained and aggravated inflammatory environment that impairs myoblast differentiation, and leads to enhanced myogenic proliferation. These results demonstrate why prolonged inflammation occurs after acute muscle injury and provide a new target for the regulation of muscle regeneration.

Research perspectives

Given the pathophysiological significance of the findings of this study, further studies are needed to elucidate the mechanisms responsible for these effects which deserve investigation. It is hoped that further studies will identify specific targets involved in muscle regeneration and fibrosis, such as lncRNAs and miRNAs.