Effect of GPVI Affimers on thrombus formation in vitro. Human whole blood was incubated in the presence or absence of GPVI Affimers (Scaffold, M17, D22, and D18; 10 μg/mL) for 15 minutes and perfused through collagen (50 μg/mL) coated microfluidic chips at 1000 per second for 2 minutes. After 2 minutes of flow, nonadherent platelets were washed off with phosphate-buffered saline for 3 minutes. Images of stably adherent platelets and thrombi were taken by fluorescence microscopy and quantified using ImageJ. Data presented as representative images (scale = 20 μm) (A) and percentage surface coverage (B) at 2 minutes (repeated measures 1-way analysis of variance with Šídàk multiple comparisons test vs scaffold; ∗P < .05). (C-F) Percentage surface coverage over time up to 2 minutes. Data presented as mean ± SD; n = 5.