Myoscaffolds demonstrate differential matrix components across muscular dystrophies

Abstract

ABSTRACTPathological remodeling of the extracellular matrix (ECM) underlies many fibrotic disorders, including muscular dystrophy. In fibrotic disorders, large matricellular proteins like proteoglycans and glycoproteins, and smaller secreted factors are progressively deposited into the matrix. Tissue decellularization uses detergent treatment to remove the cellular component, leaving behind intact the matrix components. Decellularized ECMs (or dECMs) have most commonly been studied in intact organs, but more recently, this method has been adapted to tissue sections on slides. We generated dECM from genetically different mouse models of muscular dystrophies including dystrophin-deficient, γ-sarcoglycan-deficient, and dysferlin-deficient mice, as well as analyzing distinct background mouse strains known to alter the ECM. Formalin fixed samples were assessed for complete decellularization, preservation of ECM architecture, and protein retention using histological staining and immunofluorescence microscopy. Excess collagen deposition correlated with fibrosis severity across the different dystrophic models. Each muscular dystrophy subtype demonstrated excess decorin deposition in the matrix. Dystrophin- and γ-sarcoglycan-deficient muscles displayed excess thrombospondin 4, while dysferlin-deficient muscle had excess decorin but not excess thrombospondin 4. Annexins A2 and A6 were increased across all dystrophic dECMs, but annexin deposition was greatest in dysferlin-deficient muscular dystrophy. In this model, annexin A2 was diffusely increased but annexin A6 was found in discrete regions of marked excess protein within the matrix. These studies highlight the differential nature of the core matrisome and its associated proteins in different forms of muscular dystrophy, where these proteins are positioned to influence the surrounding myofibers and inflammatory infiltrate.