Programfüzet (PDF) - DE OEC Tudományos Diákköri Tanács

Shlomit Mendelbaum, Ph.D. IUniversity Debrecen, Clinical Research CentreSYSTEMATIC STUDY ON COLLAGENS IN VWF AND PLATELETBINDINGCollagens are major constituents of the extracellular matrix of the vesselwall and play an essential role in its thrombogenicity. Types I,III,IV,V,VI,VIII,and XIII have been identified in the vessel wall and are potential substrates forplatelet adhesion. The von Willebrand Factor (VWF) is a multimeric protein thatmediates platelet adhesion to exposed subendothelium (i.e. collagen) at sites ofvascular injury under conditions of high flow/shear stress as in the large arteries,arterioles, and stenosed coronary. The latter clinical situation is often associatedwith platelet thrombus formation. Many studies highlight the role of VWF andit’s binding to collagen in the thrombus formation. However, the collagens aredifferent not only by the type and species but by the preparation method in thosestudies. The aim of the present work is to see how the treatment influences theVWF and platelet binding capacity of isolated human type I, III and IVcollagens.Lyophilized collagens were dissolved in 0.05 mol/L acetic acid and keptat +4 °C as 1 g/L stock solutions. 0.1 or 0.01 g/L working solutions were madeby further dilution with the acetic acid or phosphate buffer. 96 well plates orplastic microscope coverslips were coated with the working solutions. Purifiedhuman VWF was applied into the wells and binding was measured by HRPOlabelled polyclonal antibody. Platelet binding to the coverslips from circulatinganticoagulated whole blood was observed by light microscope. VWF bindingwas very good to collagen type I and III coated from buffer working solutionsovernight. Binding reduced gradually when working solutions stored longer thentwo days in refrigerator. However, VWF binding was very poor when aciddiluted working solutions were used for coating. Type IV collagen did not bindVWF at any conditions. Platelet binding was similar to the different type ofcollagens and the effect of coating from acid or buffer solution was hardlydistinguishable at the applied high shear stress. Our results suggest that theVWF binding is highly influenced by the collagen conformation what isdifferent in acid and buffer solution, while platelet binding is hardly effected.Témavezető: Dr. Jolán Hársfalvi