Selsby, J. T. | Search bioRxiv

bioRxiv2025

Characterization of Gait Kinematics and Muscle Function in Becker Muscular Dystrophy Pigs: a pilot study

Vertebrate animal models of Becker muscular dystrophy (BMD) have been developed. Here, we characterized the gait kinematics and muscle function of a naturally occurring BMD pig model of dystrophin insufficiency. BMD pigs tended to have alterations in hip range of motion (ROM): hip (67%, 95% CI -0.64 to 14.12 degrees). While parameters were unaltered in extensor muscles, the dystrophin levels in flexor tibiotarsal joint muscles correlated with fatigue index as well as reduced isometric force (48%, 95% CI -1.86 to -0.61 N-m), and a 33% increase in fatigue index (95% CI -36.25 to 96.71 percent); the extensor muscles had no observable reductions in muscle force, with a 48% increase in fatigue index (95% CI -232.6 to 472.6 percent). Histological analysis of muscle biopsies supported a BMD phenotype in the flexor muscles of BMD pigs, with a 75% (95% CI -55.14 to -15.66 percent) decrease in large and a 43% (95% CI 17.74 to 57.38 percent) increase in small muscle fiber cross-sectional area. Dystrophin protein abundance was 28% less in flexor muscles from BMD pigs (95% CI -49.63 to 11.41 arbitrary units). Together, our model may serve as a clinically relevant model of BMD to assess safety and efficacy of therapeutics.

pathology↗

bioRxiv2020

Satellite cell-derived extracellular vesicles reverse peroxide-induced mitochondrial dysfunction in myotubes

Satellite cells (SCs) are muscle-specific stem cells that have a central role in muscle remodeling. Despite their therapeutic potential, SC-based therapies have been met with numerous logistical challenges, limiting their ability to effectively treat systemic muscle diseases, such as Duchenne muscular dystrophy (DMD). Delivery of SC-derived extracellular vesicles (SC-EVs) may unlock the potential offered by SCs and overcome their numerous limitations. PurposeThe purpose of this investigation was to determine the extent to which SC-EVs could restore mitochondrial function in cultured myotubes following oxidative injury. MethodsSC-EVs were isolated from cultured SCs from C57 mice and quantified using nanoparticle tracking analysis (NTA). C2C12 myotubes were cultured and divided into four treatment groups: untreated control, treated for 24 h with SC-EV, 24 h exposure to 50 M H2O2 followed by a 24 h recovery period with no treatment, or 24 h exposure to 50 M H2O2 followed by a 24 h treatment with SC-EV. Inter-group differences in mitochondrial function were assessed via one-way ANOVA with Tukey post hoc analysis (p<0.05). ResultsGiven the seeding density used, we calculated that each SC releases approximately 2.35 x 105 {+/-} 3.10 x 104 EVs per 24 h. Further, using fluorescent microscopy, we verified SC-EVs deliver cargo into myotubes, some of which was localized to the mitochondria. H2O2 exposure resulted in a 42% decline in peak mitochondrial respiration (p=0.0243) as well as a 46% reduction in spare respiratory capacity (p=0.0185) relative to the untreated control group. Subsequent treatment with SC-EVs (3.12x108 SC-EV; 24 h) following H2O2 exposure restored 76% of peak mitochondrial respiration (p=0.0187) and 84% of spare respiratory capacity in the damaged myotubes (p=0.0198). SC-EVs did not affect mitochondrial function in the undamaged myotubes. ConclusionCollectively, these data demonstrate SC-EVs may represent a novel therapeutic approach for treatment of myopathies associated with mitochondrial dysfunction.

physiology↗