Tomatidine Attenuates Inflammatory Responses to Exercise-Like Stimulation in Donor-derived Skeletal Muscle Myobundles

Donor-derived myotubes offer a pre-clinical model for studying muscle biology, the effects of exercise-like electrical stimulation, and assessing drug efficacy and toxicity. We engineered a 3D muscle microphysiological system from myoblasts isolated from vastus lateralis of young and older adults. Over a three-week differentiation process, we applied two cycles of low frequency electrical stimulation daily for seven days generating functional, mature myobundles, as confirmed by gene expression profiling. Both young- and old-derived myobundles showed synchronous contraction in response to electrical stimulation, however, the contraction magnitude was reduced in old-derived myobundles compared to young-derived myobundles. We then assessed the donor-specific response to tomatidine, a steroidal alkaloid found in the skin of green tomatoes, known to inhibit muscle atrophy and promote skeletal muscle hypertrophy. Bioinformatic analyses revealed that infusion of tomatidine during electrical stimulation modulated the IL-6/JAK/STAT3 pathway. The contraction magnitude decreased in the young-derived myobundles treated with tomatidine compared to vehicle-treated controls, while no significant difference was observed in the old-derived myobundles. Secretome analysis revealed age-related changes in secreted proteins linked to inflammation and extracellular matrix remodeling. Notably, tomatidine attenuates the inflammatory and extracellular matrix remodeling responses in the myobundles triggered by electrical stimulation, partially preventing the secretion of proinflammatory proteins. This intervention strategy helps balance muscle adaptation and repair, while limiting excessive proinflammatory responses. Our microphysiological system provides a valuable platform for investigating signaling pathways involved in muscle function, and pharmacological responses, advancing the understanding of age-related muscle biology.