VWF-ADAMTS13 axis and Weibel Palade body exocytosis in SCD children treated with hydroxycarbamide compared to blood transfusion. Comparisons between HC and BT cohorts are shown including (A) VWFpp/VWF:Ag ratio and (B) FVIIl:C levels. (C) Correlation between FVIII:C and VWF:Ag. (D) Comparisons between HC and BT cohorts are shown for FVIII:C/VWF:Ag ratio, (E) angiopoietin-2, and (F) osteoprotegerin. Comparisons between groups were assessed by the Mann-Whitney U test. Correlations were evaluated using the Spearman rank correlation test; ns, not significant; ∗∗P < .01, ∗∗∗P < .001, and ∗∗∗∗P < .0001.