Impairment in the storage of the WPBs components, Ang2 and P-selectin, in patients’ endothelial cells. (A) Storage of VWF (green) and Ang2 (red) in WPBs was visualized by immunofluorescence staining of normal ECFCs (upper) and index patient ECFCs (IP-ECFCs; lower). The merge of green and red channels (with the focused region of interests) displays colocalization of VWF with Ang2 in healthy ECFCs, whereas strongly deficient VWF/Ang2 colocalization was perceived in IP-ECFCs. Scale bars, 10 µm. (B) The 3D topographic view of the merged channels of the ECFC images shown in panel A, generated by Zeiss Zen blue software. (C) The colocalization coefficients (of VWF and Ang2) were determined from at least 30 regions of interest from 2 independent experiments. (D) Fixed healthy ECFCs (upper) and IP-ECFCs (lower) were costained with antibodies detecting VWF (green) and P-selectin (red). The merge of green and red channels (with the focused regions of interest) demonstrates colocalization of VWF with P-selectin in healthy ECFCs, whereas IP-ECFCs show diminished colocalization of VWF/P-selectin. Scale bars, 20 µm. (E) Colocalization coefficients (of VWF and P-selectin) from at least 30 regions of interest from 2 independent experiments. Data are means ± SEM. ***P < .001 (unpaired Student t test).