Résumé :
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Myoblast transplantation remains a promising therapeutic approach in the treatment of several muscular disorders including Duchenne Muscular Dystrophy. Nevertheless, such therapies are limited by a massive early cell death following injections. Low molecular weight dextran sulfate (DXS), a sulfated polysaccharide, has been reported to act as an endothelial cell protectant inhibiting complement and natural killer (NK) cell-mediated endothelial cell damage. In the present study, we investigated the efficacy of DXS to protect human myoblasts from apoptosis and from allogeneic NK-cell mediated cytotoxicity. Its capacity to modulate the IFNg signaling pathway was evaluated by flow cytometry. Cell survival was quantified by non-invasive luciferase-based bioluminescence imaging after intramuscular transplantation in NOD/SCID mice. In vitro, we observed a dose dependent binding of DXS to the cells and this binding correlates positively with inhibition of staurosporine-induced apoptosis. DXS treated myoblasts were dose dependently protected from NK cell-mediated cytotoxicity. The increased expression of human MHC class II molecule HLA-DR and ICAM-1 following IFNg stimulation was significantly reduced in human myoblasts pretreated with DXS. In vivo, we observed a significant 2-fold increase in myoblast survival at 1 day (77.9 ± 10.1% vs 39.4 ± 4.9%; P = 0.0009) and at 3 days (38.1 ± 8.5% vs 15.1 ± 3.4%; P = 0.01) post injection respectively in the DXS treated group as compared to the untreated group (mean ± SEM, n=7). No significant differences were observed at 7 days (8.0 ± 2.1 % vs 3.6 ± 0.7%; P = 0.06) and at 14 days (3.6 ± 2.8 % vs 2.5 ± 0.7%, P = 0.2) post injection. This study shows a role for DXS in reducing myoblast injury in vitro and in vivo up to 3 days after DXS treatment of the cells. These data identify DXS as a potent protective molecule against early myoblast death post transplantation.
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