Résumé :
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Sickle cell disease (SCD) is an inherited blood disorder that leads to the production of abnormal haemoglobin (Hb), called HbS. In previous experiments, we have shown that sickle cell trait (SCT) carriers (heterozygous form of the disease, characterized by a percentage of HbS lower than 50%, typically 35-40%) displayed a significant muscular remodelling. This remodelling included a lower oxidative capacity (Vincent et al. 2010a) and a microvascular reorganization/rearrangement (Vincent et al. 2010b). Concerning the microvascular remodelling, SCT carriers displayed i) a lower capillary density, ii) a lower capillary tortuosity and more importantly iii) an enlargement of the microvessels. Because, sickle cell disease subjects (homozygous form of the disease) have more than 50% of HbS (typically 75-80%), we tested the hypothesis that SCD subjects would be subjected to the same muscular remodelling than SCT carriers, but even in deeper proportions. The consequences of SCD on skeletal muscle oxidative capacity and microvascular network were assess by comparing the results obtained in 10 control subjects (C), 10 sickle cell trait carriers (SCT) and 7 sickle cell disease subjects (SS). From a biopsy of the vastus lateralis muscle we assessed the activity of the citrate synthase (CS), the fibre types distribution, the surface area of the fibres, the capillary density (CD), the capillary tortuosity (CapTor) and the microvessels diameter (MD) and surface area (MSS). SS subjects displayed a lower CS activity and a general amyotrophy. As expected, the higher the proportion of HbS, the lower the capillary density and tortuosity and the larger the microvessels, although a direct cause-effect relationship was not demonstrated. The present study shows for the first time significant alterations in oxidative capacity and microvascular network of the skeletal muscle in SCD subjects.
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