Résumé :
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Duchenne Muscular Dystrophy (DMD) is an X-linked genetic disorder characterized by an early onset and rapidly progressing muscle degeneration due to the absence of functional dystrophin protein. Damaged muscle fibres can be regenerated by their muscle-residing stem cell population called satellite cells (SCs), underlying the myofibre basal lamina. Following activation, SCs proliferate extensively, fuse with the damaged fibre and return to quiescence to maintain the stem cell pool. Long-term correction of dystrophic muscle and SCs requires the insertion of a functional dystrophin gene copy into the mutated genome. Lentiviral vectors (LVs) hold great potential as a gene therapy tool for DMD, as they stably integrate their genome into dividing and non-dividing cells, thereby providing long-term expression in both proliferating myoblasts and post-mitotic myofibres. However, physiological protein levels and restriction of transgene expression to only muscle tissue is favored to avoid off-target transduction and to circumvent associated safety concerns. Here, we compare LVs carrying either a strong viral, a muscle-specific or a housekeeping promoter and assess variances in expression levels, as well as differences in integration and transduction efficiencies. Transgene expression driven by the viral vector did not alter the potential of SCs to differentiate and self-renew in vitro. Possible effects on regeneration will be further assessed in vivo by engrafting transgene-expressing SCs into dystrophin-deficient host mice. Notably, human myoblasts showed significantly enhanced transduction efficiencies compared to murine cells, thus underpinning the great potential of LVs as a future tool to stably correct human DMD stem cells possessing muscle regenerative properties.
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