FIGURE 4.

Ex vivo thrombogenicity testing of micropattern feature size under physiologic whole blood flow. Tubular micropatterned PVA (2, 5, or 10 µm gratings, n = 6) were tested in an ex vivo shunt model to quantify dynamic platelet attachment, rate of platelet attachment, end-point fibrin, and luminal area of the grafts. Micropatterned gratings were oriented parallel to the direction of blood flow. Collagen-coated ePTFE (n = 2), ePTFE (n = 2), and planar PVA (n = 2) were run as animal controls. (A) Platelet accumulation was quantified over 60 min whole blood exposure and normalized to the axial length for all grafts. Statistical analyses were performed only on the micropatterned PVA. There were no significant differences found between the micropatterned PVA. (B) The rate of platelet attachment was quantified for the linear range of dynamic platelet accumulation. We observed a trend for increasing rate of attachment as feature size increased. A significant increase in rate was observed for the 10 µm gratings compared to the 2 µm gratings. (C) Fibrin data were quantified and normalized to the axial length for all grafts. Significant differences were observed between 10 µm gratings compared to the 2 and 5 µm gratings. (D) The average luminal area of the grafts after exposure to whole blood flow were quantified using microCT image analysis. Cross-sectional area per slice of the lumen were analyzed for each graft. Significant differences were observed between 2 µm gratings compared to the 5 and 10 µm gratings. *, **, and *** indicate statistical significance (p < 0.05, 0.01, 0.001, respectively).