Storage of VWF in BOECs. BOECs derived from a healthy donor or patients with mutations as indicated were grown on collagen type 1–precoated coverslips until confluent. (A-F′) Cells were fixed and stained for VWF. The punctate staining indicates storage of VWF in WPB, whereas the diffuse staining in (D-F) indicates VWF retained within the ER. (G) Representative image showing that the diffuse VWF staining observed in BOECs derived from the patient heterozygous for p.Cys2693Tyr was colocalized with the PDI. BOECs were fixed and stained for VWF (middle, green) and the ER marker PDI (right, red). Merge of VWF and PDI staining is also shown (left). Note that the majority of WPB observed in BOECs derived from the patients heterozygous for VWF p.Ser1285Pro, p.Leu1307Pro, and p.Cys2693Tyr were short or round instead of elongated, as seen in (A). (F′) Cell derived from the patient heterozygous for p.Cys2693Tyr with WPB of normal morphology. (Scale bars, 5 μm.) All images were taken by Leica SL confocal laser scanning microscopy with a 63×/1.40 NA oil objective.