Freezing Injury in Mouse Masseter Muscle to Establish an Orofacial Muscle Fibrosis Model

Summary

The goal of this protocol is to establish an orofacial muscle fibrosis model. Comparison of the histology between mice masseter and tibialis anterior muscle after freezing injury confirmed masseter muscle fibrosis. This model will facilitate further investigation into the mechanism underlying orofacial muscle fibrosis.

Abstract

Orofacial muscle constitutes a subset of skeletal muscle tissue, with a distinct evolutionary trajectory and development origin. Unlike the somite-derived limb muscles, the orofacial muscles originate from the branchial arches, with exclusive contributions from the cranial neural crest. A recent study has revealed that regeneration is also different in the orofacial muscle group. However, the underlying regulatory mechanism remains to be uncovered. Current skeletal muscle regeneration models mainly focus on the limb and trunk muscle. In this protocol, dry ice was used to induce freezing injury in the mouse masseter muscle and tibialis anterior muscle to create an orofacial muscle fibrosis model. The temporal dynamics of muscle satellite cells and fibro-adipogenic progenitors were different between the two muscles, leading to impaired myofiber regeneration and excessive extracellular matrix deposition. With the help of this model, a deeper investigation into muscle regeneration in the orofacial area could be carried out to develop therapeutic approaches for patients with orofacial diseases.

Introduction

Orofacial muscles are critical in daily physiological activities such as mastication, speech, respiration, and facial expression¹. In congenital orofacial deformities, however, these muscles exhibit atrophic and fibrotic alterations, leading to impaired body health and social cognition². Facial reconstructive surgery remains the first-line treatment, but up to 30-70% of postoperative patients still suffer from muscle loss and muscle dysfunction^3,4 The failure of orofacial muscle regeneration has been attributed to intrinsic factors, which cannot be corrected by s....

Protocol

All animal procedures in this study were reviewed and approved by the Ethical Committee of the West China School of Stomatology, Sichuan University (WCHSIRB-D-2020-114). Male C57BL/6 mice (5 weeks old) were raised in a humidity-controlled (53 ± 2%) and temperature-controlled (23 ± 2 °C) facility and were on a 12 h light/dark cycle. See Table of Materials for details related to all materials, reagents, and instruments used in this protocol.

1. Freezing inju.......

Discussion

There are a variety of injury models for studying skeletal muscle regeneration, including the use of physical, chemical, and surgical stimuli^{10,11,12,13,14,15,16}. Cardiotoxin and barium chloride are the two most widely used chemicals to initiate muscle regeneration¹⁰<.......

Materials

Name	Company	Catalog Number	Comments
1 mL syringe	Shifeng Medical Apparatus and Instrument (Chengdu, Sichuan, China)	1-ml syringe	/
Acetone	Chron Chemicals	Aceton	/
Adhesion microscope slides	Citotest Scientific	188105	/
Animal depilatory	Phygene Scientific	PH1877	/
BSA (bovine serum albumin)	Solarbio Life Sciences	A8010	/
DAPI	Solarbio Life Sciences	C0065	/
Donkey anti-goat Alexa Fluor 488	Abcam	ab150129	1:200
donkey serum	Solarbio Life Sciences	SL050	/
Dry Ice	Sinrro Technology (Chengdu, Sichuan, China)	rice-shaped dry ice	/
IFKine Red Donkey anti-rabbit	Abbkine Scientific Company	A24421	1:200
Insulation barrels (big)	Thermos	D600	/
Insulation barrels (small)	Polar Ware	250B	/
Isoflurane	RWD Life Technology Company (Shenzhen, Guangdong, China)	R510-22	/
Isopentane	MACKLIN	M813375	/
Laminin	Sigma-Aldrich	L9393	1:1000
Liquid nitrogen	Sinrro Technology (Chengdu, Sichuan, China)	/	/
M.O.M kit	Vector Laboratories	BMK-2202
Mice	Dashuo Biological Technology Company(Chengdu, Sichuan, China)	5 weeks old	/
mounting medium	Solarbio Life Sciences	S2100	/
Nertral balsam	Solarbio Life Sciences	G8590	/
Pax7	Developmental Studies Hybridoma Bank	Pax7	1:5
Pdgfra	R&D systems	AF1062	1:40
Sirus Red Staining Kit	Solarbio Life Sciences	G1472	/
Surgical instruments (forceps, scissors, needle holder, scalpel, and suture)	Zhuoyue Medical Instrument (Suqian, Jiangsu, China)	/	/
Tissue-tek OCT	Sakura	4583	/
Triton	Shanghai Scigrace Biotech	ABIO-Biofroxx-0006A	/
Zoletil	Virbac	Zoletil 50	/