Exercise-mimetic exosomes rescue redox, mitochondrial, and osteogenic defects to restore muscle-bone communication in dystrophic co-cultures

Background & Objective: Dystrophin deficiency leads to a progressive musculoskeletal pathology marked by oxidative stress, chronic inflammation, and premature senescence, which disrupts muscle-bone crosstalk. To determine whether this crosstalk is mediated by exosome cargo, we profiled exosomes derived from primary human DMD myotubes. These vesicles exhibited a distinctly pathogenic signature, characterized by lower levels of IL-10, SOD2, FNDC5, and myogenic microRNAs, alongside elevated miR-34a, NOX2, and TGF-β1, supporting their capacity to propagate oxidative and fibrotic stress. Exercise-mimetic exosomes “Exerosomes”, generated through physiologic mechanical loading, may counteract these cues. We evaluated whether Exerosomes can mitigate the degenerative effects induced by DMD pathology and restore mitochondrial, redox, and osteogenic pathways in a human primary myotube-osteoblast co-culture model. Hypothesis: We hypothesized that dystrophin-deficient myotubes release exosomes carrying pro-degenerative cargo that promote oxidative stress, inflammation, and senescence in recipient osteoblasts, and that Exerosome supplementation would reverse musculoskeletal degeneration by restoring mitochondrial and redox homeostasis. Methods: We used human myotube-osteoblast transwell co-cultures (n=12/group) for 5 days: (1) Healthy; (2) DMD (untreated); (3) DMD + 100 nM daily antagomiR-34a; (4) DMD + Exerosomes (1×10 9 particles/mL/day). In all conditions, osteoblasts were derived from healthy donors, while the myotube served as the DMD source. Media and cells were harvested for molecular and functional analyses. Endpoints included osteogenic markers, myogenic regulators (MYOD1, MYOG), redox and mitochondrial indices, cytokine expression, senescence markers, and Seahorse-based respiration. Results: DMD cultures developed a broad degenerative phenotype. Osteogenic signaling declined, reflected by elevated RANKL/OPG ratios, reduced ALPL and BGLAP, and diminished mineralization. Myogenic differentiation was substantially impaired, with marked reductions in MYOD1 and MYOG. Redox homeostasis deteriorated, with increased NOX2, heightened reactive oxygen species, and loss of antioxidant and mitochondrial regulators, including SOD2, PGC-1α, and SIRT1. These alterations were accompanied by increased inflammatory and pro-fibrotic cytokines and a pronounced senescent phenotype marked by higher p16, p21, and SA-β-gal activity. Mitochondrial respiration declined across major oxygen-consumption parameters, accompanied by a metabolic shift toward increased glycolysis. Exerosomes, enriched in reparative cargo such as PGC-1α, FNDC5, and IL-10, reversed these pathological responses. Treated DMD cultures exhibited restored osteogenic output, improved mineralization, recovery of MYOD1 and MYOG, strengthened redox balance, improved mitochondrial respiration, and reduced inflammatory and senescent signaling. AntagomiR-34a provided partial rescue, underscoring miR-34a as a mechanistic contributor to DMD exosome pathology but demonstrated narrower efficacy than Exerosomes. Conclusion: Exosomes from dystrophic muscle carry a pathogenic cargo capable of driving oxidative, inflammatory, mitochondrial, and osteogenic dysfunction, disrupting muscle-bone crosstalk. Exercise-mimetic exosomes generated by physiological loading effectively counteract these degenerative signals, restoring muscle-bone communication. These findings support advancing Exerosomes as a mutation-agnostic therapeutic strategy for DMD and justify progression to in vivo evaluation. Funding: Supported by Fight DMD Association and NASA EPSCoR. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.