Summary
Severe sepsis in children or adults may cause a life-threatening coagulopathy, with
widespread consumption of activated protein C (APC); recombinant human APC (rhAPC)
is a promising candidate anticoagulant treatment. We investigated the effects of rhAPC
and other anticoagulants on coagulation triggered by adding small quantities of lipidated
tissue factor to human umbilical-cord plasma in vitro. rhAPC, unfractionated heparin (UH),and melagatran (a direct thrombin inhibitor)
were studied individually, and in combinations of rhAPC with either UH or melagatran.
rhAPC alone dose-dependently prolonged the activated partial-thromboplastin time (aPTT)
but not the prothrombin time (PT), and dose-dependently suppressed two indices of
thrombin generation, namely prothrombin fragment F 1.2 (F 1.2) generation and thrombin–antithrombin
(TAT) complex formation. UH alone dose-dependently prolonged the aPTT but not the
PT, while melagatran alone dose-dependently prolonged both the aPTT and the PT. Adding
either UH or melagatran dose-dependently augmented the capacity of rhAPC to suppress
F 1.2 generation (with addition of UH showing a greater effect) and TAT formation
(with addition of melagatran showing a greater effect). Both the capacity of UH to
prolong the aPTT and the capacity of melagatran to prolong the aPTT and the PT were
augmented by adding rhAPC. In our in-vitro study, adding either UH or melagatran augmented the capacity of rhAPC to suppress
thrombin generation in human umbilical-cord plasma, with the anticoagulant effect
of melagatran being more predictable than that of UH. Hence, combining rhAPC with
melagatran might be a valuable therapeutic option in patients with severe sepsis.
Keywords
Anticoagulation - heparin - melagatran - recombinant human activated protein C - thrombin