Adenovirus activates endothelial cells in vitro and induces release of ultra-large molecular weight VWF as well as EMPs following intravenous administration in mice. (A) BOECs were treated with 3 doses of adenovirus (V1-3) for 6 hours. Cells were then harvested, washed, and stained with fluorescent-labeled anti–human VCAM-1 and assessed by flow cytometry. BOECs treated with LPS were used as a positive control and LPS data were set at 100% (average of 3 experiments). (B) BOEC culture media was collected at 24 hours following adenovirus treatment for VWF quantitation. There was a non–dose-dependent increase in VWF levels when compared to the untreated cells. (C) Plasma samples from Balb/C mice were collected 1 to 2 hours following intravenous administration of adenovirus. VWF levels increased significantly (11.9-fold above preinjection level; upper panel) and ultra-large molecular weight VWF multimers appear on multimer analysis of murine Balb/c plasma (lower panel). The figure shows an increased multimer density (increased VWF) as well as ultra-large multimers in the 7 adenovirus-treated mice (lanes1-7) compared to control mouse plasma (C lanes, represented by the two arrows). The dotted line shows highest molecular weight multimer in normal mice. (D) The number of EMPs in plasma obtained from Balb/c mice after intravenous virus administration based on CD62E expression increases significantly following administration (n = 3, P = .03). Values shown are the mean ± SEM.