ADAMTS13 and thrombotic thrombocytopenic purpura: Recent studies in mice models reported that plasmin can function as a back-up for ADAMTS-13 to proteolyze VWF and mitigate TTP symptoms, but only in conditions of supraphysiological increased plasmin activity to overcome the inhibition by α2-antiplasmin and plasminogen activator inhibitor 1 (PAI-1) (17).