September 2025 - Carla Tripisciano and Johannes Thaler

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Dr. Carla Tripisciano, MSc and Ap. Prof. Priv.-Doz. Dr. Johannes Thaler, PhD

MedUni Wien RESEARCHER OF THE MONTH September 2025

Saliva contains extracellular vesicles. These extracellular vesicles expose complexes of tissue factor and activated factor VII that trigger blood coagulation. In the current study, we show that such coagulant extracellular vesicles are also present in saliva of persons with severe hemophilia A, that is, persons with factor VIII deficiency. Consistently, in our retrospective analysis of persons with severe hemophilia A, who do not receive prophylactic factor VIII substitution, oropharyngeal mucosal bleedings are infrequent and self-limited. Conversely, in persons with severe FVII deficiency oropharyngeal bleedings are prevalent because extracellular vesicles lack coagulant potential due to the absence of factor VII.

Selected Literature

1. Thaler J, Tripisciano C, Kraemmer D, Hau C, Samadi N, Ruf W, Pabinger I, Knoebl P, Nieuwland R, Ay C. Saliva of persons with hemophilia A triggers coagulation via extrinsic tenase complexes. Blood. 2024; 144: 2666-77. 10.1182/blood.2024025093.

2. Tripisciano C, Weiss R, Eichhorn T, Spittler A, Heuser T, Fischer MB, Weber V. Different Potential of Extracellular Vesicles to Support Thrombin Generation: Contributions of Phosphatidylserine, Tissue Factor, and Cellular Origin. Sci Rep. 2017; 7: 6522. 10.1038/s41598-017-03262-2.

3. Thaler J, Tripisciano C, Nieuwland R. Investigations on the Hemostatic Potential of Physiological Body Fluids. Hamostaseologie. 2024; 44: 377-85. 10.1055/a-2374-2903.

4. Hu Y, Hell L, Kendlbacher RA, Hajji N, Hau C, van Dam A, Berckmans RJ, Wisgrill L, Ay C, Pabinger I, Brisson A, Repa A, Nieuwland R, Thaler J. Human milk triggers coagulation via tissue factor-exposing extracellular vesicles. Blood Adv. 2020; 4: 6274-82. 10.1182/bloodadvances.2020003012.

5. Hu Y, Repa A, Lisman T, Yerlikaya-Schatten G, Hau C, Pabinger I, Ay C, Nieuwland R, Thaler J. Extracellular vesicles from amniotic fluid, milk, saliva, and urine expose complexes of tissue factor and activated factor VII. J Thromb Haemost. 2022. 10.1111/jth.15801.

6. Hell L, Wisgrill L, Ay C, Spittler A, Schwameis M, Jilma B, Pabinger I, Altevogt P, Thaler J. Procoagulant extracellular vesicles in amniotic fluid. Transl Res. 2017; 184: 12-20 e1. 10.1016/j.trsl.2017.01.003.

7. Tripisciano C, Weiss R, Karuthedom George S, Fischer MB, Weber V. Extracellular vesicles derived from platelets, red blood cells, and monocyte-like cells differ regarding their ability to induce factor XII-dependent thrombin generation. Frontiers in Cell and Developmental Biology, 2020; 8: 298.