inducing freezing injury to establish an orofacial muscle fibrosis mouse model

Etablering av en orofacial muskelfibrosemodell hos mus via en fryseskade

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 dysfunction3,4 The failure of orofacial muscle regeneration has been attributed to intrinsic factors, which cannot be corrected by surgery alone. 
The emergence of orofacial muscles is an evolutionary novelty, accompanying the complex vertebrate head and chambered heart5,6. Unlike their somite-derived limb counterparts, orofacial muscles originate from the branchial arch7. These phylogenetic and ontogenetical characters may predispose them to distinct regenerative behaviors8. It has been reported that the masseter (MAS) muscle developed severe fibrosis at the time when the tibialis anterior (TA) muscle fully regenerated after exposure to the same extent of injury1,9. However, the underlying mechanism of regeneration remains poorly understood. 
In this study, a freezing injury model of the mice masseter muscle was established to facilitate the investigation into orofacial muscle regeneration. We chose 14 days after injury as the time point for assessing fibrosis phenotype as it was the earliest time point where discernible divergence was detectable between two muscles. Complete regeneration of the MAS after injury requires at least 40 weeks1. Consistently, this study revealed a remarkable deposition of collagen following freezing injury of MAS compared to the regular regeneration of the TA at 14 days post injury. With the help of this model, further mechanistic studies of muscle atrophy and fibrosis can be carried out, which will in turn help the development of potential therapeutic avenues to promote orofacial muscle regeneration after surgery.

Forfatter Spotlight: Utforske orofacial muskelregenerering – innsikt og innovasjoner

Fryseskade i musetyggemuskel for å etablere en orofacial muskelfibrosemodell

Current skeletal muscle regeneration studies merely focus on the limb and the trunk muscle, leaving the characteristics and mechanism of orofacial muscle regeneration largely unexplored. The scope of this research is to create and easier and reliable mouse model to facilitate further investigation into muscle regeneration in the orofacial area. Recent developments review that orofacial muscles constitute a unique subset of skeletal muscle with a distinct evolutionary trajectory and developmental origin.They also exhibit different regeneration performances compared with their limb counterparts. A deeper investigation into the orofacial muscle regeneration is warranted to figure out the mechanism underlying these marked differences. The study present a rapid and reproducible method to study orofacial muscle regeneration.The half-freezing injury process took 20 minutes, and the harvest process took only 10 minutes for each mouse, and the mice can tolerate the injury well without any impairment of locomotion. Since our model allows for subsequent comparison between the fibrotic masseter muscle and the fully regenerated tibialis anterior muscle from the aspects of morphology, histology, and molecular regulation, it serves us a power for two for us to delve deeper into the underlying mechanism. Our future research will focus on the causal effects among the alterations of the resident muscle stem cells and multiple niche cells, and correspondingly developed interventions to the process of orofacial muscle fibrosis.

Induserer fryseskade for å etablere en orofacial muskelfibrose-musemodell

For å begynne, plasser den bedøvede musen på operasjonsbordet. Bruk en bomullspinne til å påføre hårfjerningspastaen på huden, som dekker tyggemuskelen og tibialis fremre muskel. Etter å ha ventet i ett til to minutter, vask pastaen med en kirurgisk klut.For å eksponere tyggemuskelen, må du først palpere langs den nedre kanten av underkjeven. Fem millimeter fra kanten, kutt opp huden langs linjen, og koble den orale kommisjonen til tragus. For å utføre frysing, bruk forkjølte tang for å holde et stykke tørris.Plasser tørrisen langs de lange aksene til tyggemusklene direkte på overflaten av muskelen og hold i fem sekunder. Bekreft at muskelen virker stiv og blekhvit umiddelbart etter at tørrisen er fjernet, og går deretter tilbake til normal farge og tekstur innen 22 til 25 sekunder. Etter at muskelen er helt restituert, lukk hudsåret med minst tre 7-0 suturer.For tibialis fremre muskel, palpere langs leggen for å finne den fremre kanten av tibiabenet. To millimeter bakre til kanten, kutt opp huden, fra kneet og slutter ved ankelen. For å utføre frysing, bruk forkjølte tang for å holde et stykke tørris.Plasser tørrisen langs de lange aksene til tibialis fremre muskler direkte på overflaten, og hold i fem sekunder. Bekreft at muskelen virker stiv og blekhvit umiddelbart etter at tørrisen er fjernet, og går deretter tilbake til normal farge og tekstur innen 22 til 25 sekunder. Etter å ha suturert hudsåret, plasser musen på en varmeplate som holdes på omtrent 38 grader Celsius.Overvåk kontinuerlig til musen gjenoppretter sin rettrefleks.

inducing-freezing-injury-to-establish-an-orofacial-muscle-fibrosis

Research

JoVE Journal

Biology

Inducing Freezing Injury to Establish an Orofacial Muscle Fibrosis Mouse Model

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

Orofacial muscle constitutes a subset of skeletal muscle tissue, with a distinct evolutionary trajectory and development origin. Unlike the somite-derived ...