Saliva from persons with hemophilia A triggers coagulation via extrinsic tenase complexes

Human saliva contains extracellular vesicles (EVs). These EVs expose extrinsic tenase complexes of tissue factor (TF) and activated factor VII (FVIIa), and trigger blood coagulation. Here, we show that EVs exposing extrinsic tenase complexes are also present in saliva of persons with severe hemophilia A, i.e. persons with FVIII deficiency. Addition of these salivary EVs to autologous FVIII-deficient blood results in FXa generation, thereby compensating for the lack of FXa generation …