Diaphragmatic-derived extracellular matrix patch exerts a positive long lasting effect on myogenic regeneration and nerve attraction when used in a surgical mouse model of diaphragmatic hernia

Treatment of large defect in congenital diaphragmatic hernia (CDH) remains a challenge. Engineered muscle tissue may help limiting the recurrence risks related to the available patches. Recently we characterized the extracellular matrix (ECM) obtained from decellularized mouse diaphragmatic muscle. This scaffold displayed important characteristics such as biomechanical features, immunomodulatory properties and ability to recruit specific myogenic progenitors. For these reasons, we developed for the first time a CDH surgical model in mouse and focused our attention on using decellularized ECM as biologic tool for the treatment of diaphragm defects. A surgical CDH mouse model with large defect was set up: Balb/c mice were used as recipients and C57Bl6/J mice as diaphragm ECM donors. Expanded polytetrafluoroethylene (ePTFE) patches were used as treatment controls. Mice were analysed after 30 and 90 days of defect closure through histology and molecular analysis. We compared the efficacy of defect closure of decellularized diaphragm ECM and ePTFE. Survival (65%) was comparable between the groups, but only ePTFE treated mice demonstrated recurrence (12.5% vs 0%). Moreover, 100% of ePTFE treated diaphragms presented a classical foreign body reaction with the formation of a fibrotic capsule. On the contrary, in ECM transplanted mice, there was no fibrosis, the scaffold promoted a good vascularization and exerted a strong activation of tissue remodelling and myogenesis with significant overexpression of both myogenic genes and proteins in respect to ePTFE animals. Moreover, Schwann cells colonised the ECM, indicating nerve re-growth inside the scaffold. ECM derived scaffolds tested in a newly developed mouse model exerted a positive effect when applied in a large diaphragm defect, influencing local remodelling, myogenic and nervous tissue regeneration in a more physiological manner in respect to standard of care prosthetic patches.