Disease exacerbation by fibroblast inclusion in Duchenne Muscular Dystrophy MYOrganoids reveals limitations of microdystrophin therapeutic efficacy

Current gene therapy approaches for Duchenne muscular dystrophy (DMD) using AAV-mediated delivery of microdystrophin (uDys) have shown limited efficacy in patients, contrasting with the favorable outcomes observed in animal models. This discrepancy is partly due to the lack of models that accurately replicate key pathogenic features associated with the severity of the human disease, such as fibrosis and muscle weakness. To tackle the translational gap, we developed a human disease model that recapitulates these critical hallmarks of DMD for investigation and therapeutic purpose. Using a muscle engineering approach, we generated MYOrganoids through co-culture, where fibroblasts play a crucial role in enabling functional maturation and allowing functional studies, such as muscle force measurements during contractions. Incorporation of DMD fibroblasts within DMD iPSC-derived muscle cells allows phenotypic exacerbation and unraveling of fibrotic signature and muscle strength loss by cell-contact-dependent communication. Although gene transfer partially restores muscle force, it fails to fully restore dystroglycan components and reduce profibrotic signaling. These findings reveal the persistence of fibrotic signatures post-gene therapy in our human DMD MYOrganoids - an aspect not fully appreciated in current models. This novel insight provides an opportunity to explore the underlying mechanisms of dysregulated cellular communication and identify new therapeutic targets for anti-fibrotic strategies to enhance gene therapy efficacy.