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The role of coagulation factor XII in propagation of coagulation
Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland.ORCID iD: 0000-0002-1920-3962
Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

The physiological relevance and function of coagulation factor XII (FXII), the first zymogen in the intrinsic pathway, has for a long time been a matter of debate. The aim of this study was to shed some light on the role of factor XII in thrombus formation with a focus on its effect during the propagation phase of coagulation. In order to study propagation of coagulation we utilized a new imaging method to measure propagation rates from an activating surface in both platelet-free plasma and platelet-rich plasma. The most essential results revealed that both FXII and its substrate FXI are located on the surface of activated platelets. The surface of preexisting clots does not support coagulation in a FXII dependent manner. However, we found strong evidence for an accelerated propagation of tissue factor initiated coagulation when contact activation of FXII simultaneously occurred in the proximity. In vivo sources for contact activation may be exposed subendothelial collagen as well as soluble and cell derived poly-anions. If such in vivo contact activation of FXII occurs, even though moderate, it could contribute to in vivo thrombus growth rate and thus be of pathophysiological importance.

National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-19177OAI: diva2:223528
Available from: 2009-06-12 Created: 2009-06-12 Last updated: 2015-03-13Bibliographically approved
In thesis
1. Imaging methods for haemostasis research
Open this publication in new window or tab >>Imaging methods for haemostasis research
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Blood is a vital part of the human physiology; a transport system that brings nutrients and oxygen to sustain living cells and simultaneously facilitates the removal of carbon dioxide and other waste products from the body. To assure the continuity of these functions, it is of uttermost importance to keep the flowing blood inside the vascular system at any cost. The principal components of the haemostatic system are the blood platelets and the plasma coagulation system, both working in concert to create a blood stopping haemostatic plug when a vessel is ruptured. In modern health care, methods for treatment and diagnostics often implicate the contact between blood and artificial materials (biomaterials). Biomaterial surfaces may activate platelets and the coagulation cascade by exposing a surface that during blood contact shares certain characteristics with surfaces found at the site of vascular injury. Therefore it is of great importance that the mechanisms behind the interactions between foreign surfaces and blood are studied in order to minimize, and if possible, prevent unnecessary reactions that may lead to thrombosis.

This thesis describes two important methods to study blood – surface interactions in terms of surface induced plasma coagulation and platelet adhesion/aggregation. The method ‘Imaging of coagulation’, a coagulation assay based on time-lapse image capture of the coagulation process was developed during the course of this work. The use of images enables the method to answer questions regarding where coagulation was initiated and how fast coagulation propagates. Such questions are highly relevant in the study of blood-biomaterial interactions but also in general haemostasis research. In vivo, platelet adhesion and aggregation are events that always proceed under flow conditions. Therefore we also developed a cone-and-plate flow model to study these mechanisms under similar conditions in vitro. The cone-and-plate setup was found to be a flexible platform and was used for both blood compatibility testing of potential biomaterials as well as for general haemostasis research.

With the above mentioned methods we tested the haemocompatibility of glycerol monooleate (GMO), a proposed substance for use in biomaterial applications. It was found that GMO did not activate coagulation to any great extent either in plasma or in whole blood.

Surface induced coagulation and platelet adhesion was also studied on PEG-containing hydrogels and compared with hydrogels constructed from three different non-PEG-containing monomers. It was concluded that all the grafted hydrogels, in particular those produced from the monomers 2-hydroxyethyl methacrylate (HEMA) and/or PEG- methacrylate (PEGMA), demonstrated good haemocompatibility.

Supported phospholipid bilayers were used to investigate the relationship between surface charge and procoagulant activity. The coagulation process was studied in a straightforward manner using the imaging of coagulation setup. We concluded that the content of negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-L-serine] (POPS) in the bilayer must exceed ~ 6% for the bilayer to exert procoagulant activity.

The physiological role of factor XII in human haemostasis and thrombosis was investigated in the imaging of coagulation setup and the cone and plate setup by the use of surfaces with thrombogenic coatings. We found that tissue factor initiated coagulation could be greatly accelerated by the presence of contact activating agents in a platelet dependent manner.

In conclusion, the method ‘Imaging of coagulation’ and platelet adhesion/aggregation in the cone-and-plate flow model are both versatile methods with many possible applications. The combination of the two methods provides a solid foundation for biomaterial and haemostasis research.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 61 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1131
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-19178 (URN)978-91-7393-621-7 (ISBN)
Public defence
2009-06-01, Aulan, Hälsans hus, Campus US, Linköpings Universitet, Linköping, 13:00 (English)
Available from: 2009-06-12 Created: 2009-06-12 Last updated: 2009-08-21Bibliographically approved

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