Hemostatic safety characterization, biodistribution, and pharmacokinetic parameters of SCE5-scuPA in the mouse. (A) Tail bleeding safety studies with SCE5-scuPA, showing the average total blood volume lost from a mouse tail wound over 20 minutes; 150 U/g is the highest SCE5-scuPA dose that does not disrupt hemostasis. n = 5 to 9. (B) Representative near-infrared fluorescence scans of perfused organs collected 4 hours after injection of Cy7.5-conjuated SCE5-scuPA (0.5 μg/g). (C) Quantification of the biodistribution of SCE5-scuPA by mean fluorescence intensity (MFI) per pixel in major organs. SCE5-scuPA predominately accumulates in the spleen and liver. n = 3. (D) Representative near-infrared fluorescence scans of blood samples collected at the designated time points. (E) Representative blood clearance plot of blood MFI per pixel vs time, fitted to a one-phase exponential decay nonlinear regression, after intravenous administration of Cy7.5-conjuated SCE5-scuPA (150 U/g). SCE5-scuPA is rapidly cleared from the circulation, with a half-life of 3 minutes ± 30 seconds. n = 4. All data are presented as mean ± standard error of the mean. ∗P < .05, ∗∗∗P < .001, ∗∗∗∗P < .0001 by one-way analysis of variance with Tukey’s post hoc analysis. AU, arbitrary units.