Résumé :
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Communication n° 157 Introduction : Myoblast transplantation is a widely investigated cell therapy technique for the potential treatment of muscle injury, cardiac failure and inherited myopathies. We have showed recently that pig is an adequate large animal model for exploring myoblast transplantation strategies applicable in patients. Nevertheless, this approach is limited by an important donor cell death after injection. In this study, our goal is to evaluate if heat-shock (HS) pre-treatment can protect porcine myoblasts after autologous transplantation in intact skeletal muscle. Methods : HS treatment was assessed by incubating porcine myoblasts at 42°C for 1 h, 24 h before the transplantation or before the in vitro test. Over-expression of HS proteins (HO-1 and hsp70) was analyzed by flow cytometry and Western blot. To follow cell survival, myoblasts were labeled with 3H-thymidine and transplanted (1.6 x 106 cells per injection) into intact pig muscle. Biopsies were performed at the implanted sites up to 5 days after injection for measurement of the remaining 3H scintillation rate. Results : Untreated or HS pre-treated cells showed no significative differences in their myogenic characteristics. Flow cytometry and western-blot analysis indicated a fivefold over-expression of HO-1 and hsp 70 levels 24h after the HS treatment. In vivo (n=7), the HS treatment improved MPC survival by twofold at 48 h (52.3 Æ 8.2% versus 28.8 Æ 6.3%; p=0.014) and by threefold at 120 h (26.3 Æ 5.5% versus 8.8 Æ 2.5%; p=0.004). No significant differences were observed at 24 h (67.7 Æ 8.3% versus 58.8 Æ 8.3%). Conclusions : HS treatment partially protects porcine myoblasts from early donor-cell death in vivo and may represent a novel therapeutic concept applicable in human. Long-term expression of protective genes, such as HO-1, may represent a promising strategy to improve myoblast survival after transplantation.
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