Passive-Stretch Induced Skeletal Muscle Injury Platform for Duchenne Muscular Dystrophy Modeling
Author(s): Maryam Fayazi
Research Objectives
Inactivity following skeletal muscle dysfunction in DMD usually causes compromised soft tissue and decreased joint range of motion. Passive stretch techniques in combination with an exercise program are used as interventions to prevent musculoskeletal complications in children with DMD. However, the exact role of stretch-based rehabilitation methods is not well established in children with DMD. In fact, the underlying molecular and cellular mechanisms of how stretch-based rehabilitation methods in dystrophin-deficient muscle fibers might worsen the disease phenotype have not been fully explained. Therefore, the purpose was to establish an in vitro stretch-induced injury model in normal and dystrophic rat skeletal muscle fibers.
Design
Randomized experimental.
Setting
Laboratory Setting.
Participants
Normal and dystrophic primary rat myoblasts (N=8) were platted on two (control and experimental) nanopatterned plates. The experimental setting was replicated three times.
Interventions
Myofibers were subjected to passive stretch on day three differentiation using the Cytostretcher device for 10 hours.
Main Outcome Measures
A electrochemiluminescence assay was used to quantify concentrations of skeletal muscle-specific injury biomarkers, FABP3, Myl3, and STnI. Two-way analysis of variance (ANOVA) with repeated measure test was used.
Results
STnI concentration was significantly higher on day four post differentiation compared to day three in the DMD-stretched group; whereas STnI concentration in all three groups did not show significant changes between the two-time points. FABP3 concentrations showed a significant increase on day four of differentiation compared to pre-stretch in both the DMD-stretched and the WT-stretched groups. However, MyL3 concentration decreased across all groups on day four of differentiation compared to day three.
Conclusions
The initial findings of this study supported the hypothesis that the passive-stretch protocol caused a greater magnitude of injury in dystrophic myofibers compared to normal. However, the preliminary findings did not support the hypothesis that dystrophin deficiency could worsen the response to passive-stretch-induced injury. These findings will guide the development of future in vitro studies for disease modeling, and to better understand the molecular mechanism(s) responsible for adaptation to exercise-induced muscle injury.
Author(s) Disclosures
The authors declare no conflict of interest.