Pre-HCT markers of endothelial activation in patients with SCD vs patients without SCD and those who later did or did not develop TA-TMA. (A) Among patients with an available baseline pre-HCT sample (SCD = 22, non-SCD = 17, total = 39), P-selectin and VCAM-1 were significantly higher in children with SCD than in those without SCD. There was no difference in syndecan-1, ST-2, or endothelin-1 in the SCD vs non-SCD cohorts (not shown). (B) There was no difference in pre-HCT levels of endothelial markers in those who later developed TA-TMA (samples available, n = 7, all patients with SCD) vs those who did not develop TA-TMA (n = 31). Box and whisker plots indicate the median and quartiles. Each value is represented by a red dot and the mean by a blue diamond.