Reduced percentages and increased levels of ROS and apoptosis in precultivated BM EPCs from corticosteroid-resistant ITP patients. The (A) percentages and levels of (B) intracellular ROS and (C) apoptosis in precultivated BM EPCs were analyzed by flow cytometry in patients with corticosteroid-resistant ITP and corticosteroid-sensitive ITP and healthy controls (Normal). (D) Mouse anti-human CD34 (green) and rabbit anti-human CD133 (red) were incubated to identify the BM EPCs. DAPI (blue) was used to stain the nucleus. In situ histological analyses of the BMBs showed that the frequency of the double-positive–stained (merged in yellow) EPCs with CD34 and CD133 was significantly reduced in corticosteroid-resistant ITP patients compared with corticosteroid-sensitive ITP patients and healthy controls according to immunofluorescent staining (scale bars, 50 μm). Subject variables were compared using the Mann-Whitney U test for continuous variables. All P values <.05 were considered significant and were provided in the figure. MFI, mean fluorescence intensity.