Fig. 4: MPI candidates show superior hemocompatibility.

A MPIs do not affect lag time in TF-initiated plasma clotting system. Clot times measured on a coagulometer in a FXII-deficient plasma clotting system with clotting initiated with 100 pM TF. Negative control was a mixture of plasma, HBS and TF without MPI added, shown as grayed area with standard deviation as gray dotted lines. Clot times of plasma with added MPI [100 μg/mL] show no significant difference in clot time relative to the negative buffer control; almost all lie within the standard deviation of the buffer control. Only UHRA-8 was significant with ****P < 0.0001. B, C Lead MPI candidates show no influence on thrombin generation in plasma. TF initiated human plasma clotting parameters in a thrombin generation assay. Buffer control represents plasma clotted with buffer. MPI, when added in lieu of buffer, show minimal effects on thrombin generation compared to UHRA-8. B Lag time. C Peak thrombin. D–F Lead MPI candidates do not influence whole blood clotting. Rotational thromboelastometry (ROTEM) of fresh citrated human whole blood clotting activated with CaCl₂. 100 μg/mL MPI was added to whole blood and buffer control was performed with each experiment, per donor. **P < 0.001, ***P < 0.0005, ****P < 0.0001. D Thromboelastrogram. E Clot time normalized to buffer control (636 ± 156 s). ****P < 0.0001. F Maximum clot firmness normalized to buffer control (53 ± 4 mm). A1-A3 and B2-B3 represent mean values +/− SD from n = 3 donors. ****P < 0.0001. G–H MPI 8 does not interfere with fibrin clot fiber thickness and morphology. Images were acquired using a Helios 650 focused ion beam scanning electron microscope. Scanning electron micrographs of fibrin clots formed in the presence of (G) Clot images were taken at three magnifications ×5000, ×10,000 and ×25,000. Images from ×10,000 are depicted. H Quantified fibrin fiber diameter. Results represent mean values +/− SD from n = 2 independent clots per group. MPI 8 normalized the polyP induced increase in fibrin diameter to that of buffer control. Results analyzed using ordinary one-way ANOVA, two-tailed, with Tukey’s multiple comparisons test. ****P < 0.0001, ns not significant.