Elevated anti-human factor Xa activity in rabbit and rodent plasma: Implications for preclinical assessment of human factor X in animal models of hemostasis

A wide variety of animal models on thrombosis and hemostasis are used in research for the preclinical assessment hemostatic agents. While vertebrate coagulome is highly conserved, human plasmas differ considerably when evaluated coagulation assays such as prothrombin time (PT), activated partial thromboplastin (APTT), calibrated automated thrombography (CAT). Here, we have aimed to provide a reference framework evaluation inhibition FXa (hFXa) various plasmas. To do so, side-by-side extrinsic intrinsic pathway was performed by means PT, APTT, CAT measurements (diluted) pooled from goats, pigs, rabbits, rats, mice, humans. Plasma anti-FXa activity assessed determining rate recombinant hFXa through chromogenic analyses immunoblotting. In general, rabbit, rat, mouse exhibited robust clotting upon stimulation both pathway, produced more thrombin during plasma dilution, displayed relatively high inhibitory activities. By comparison, goat, porcine, similar profile PT APTT assays, less comparable conclusion, observed differences parameters anti-hFXa point higher anticoagulant threshold particularly mice relative human, porcine plasma. Finally, rat found be relevant FX(a) comparison murine