Thrombus formation in vitro by soluble-phase TGFBIp. Washed platelet perfusions (5 minutes at shear rate 500−1) over type I collagen were performed in the absence or presence of soluble TGFBIp (1, 2, and 5 μg/mL). Platelet adhesion (A) and platelet spreading (B) under flow conditions were determined. Aspirin-free donors were perfused over type I collagen in the presence or absence of soluble TGFBIp for 5 minutes, and platelet deposition (thrombus formation) was monitored in vitro. (C) Microscopic picture (×200 magnification) showing thrombus formation in the presence or absence of soluble TGFBIp. The scale bar represents 10 μm. (D) Representative histograms showing the size of thrombus formation at different concentrations (2-8 μg/mL) of TGFBIp. All results are shown as the means ± SD of 3 different experiments and ANOVA. *P < .05 compared with 0 μg/mL TGFBIp.