Robust thrombus formation despite anticoagulation in COVID-19. (A-J) Thrombus and fibrin formation were assessed under arterial shear (1000 s−1) using recalcified whole blood on collagen/TF (A-F) or collagen-coated spots (G-J). Samples were stained for platelets (α-GPIbβ-Alexa647, magenta) and fibrin(ogen) (cyan). SAC (%) of platelets (B and G), platelet fluorescence intensity in AUs (C and H), morphological score evaluated by 2 blinded investigators (D and I), and fibrin(ogen) SAC (E and J) are displayed. Representative images from 1 focal plane are depicted in panel A and scale bars indicate 50 μm. (F) Thrombi were imaged in 1 focal plane using confocal microscopy, scale bar in upper images indicates 50 μm and lower images indicates 25 μm. All graphs show median ± 95% CI. Differences were analyzed using the Kruskal-Wallis test. ∗P < .05, ∗∗P < .01, ∗∗∗P < .001, ∗∗∗∗P < .0001.
