SR604 does not interfere with the cytoprotection and endothelial barrier function of APC in hemophilic mice. Eight-week-old male PROC^+/+;F8^−/− and PROC^+/+;F9^−/− mice were injected IV with either SR604 (0.5 mg/kg) or HPC4 (0.5 mg/kg), followed by intraperitoneal injection of LPS (10 mg/kg). (A) Survival rates of different groups of mice. Mice were examined every 12 hours for 3 days, and the survival rates were recorded after LPS challenge. (B-C) Plasma levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and interleukin-6 (IL-6) of mice. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001. (D-E) Representative confocal images of immunofluorescent staining of cryosections of the lungs. CD31 marks endothelial cells and CD45 labels inflammatory cells, with 4′,6-diamidino-2-phenylindole (DAPI) used for nuclear staining. CD45⁺ cells were quantified using ImageJ software.