title: Activation of coagulation and platelets is affected by the hydrophobicity of artificial surfaces.
abstract: Clot formation is a limiting factor in the use of biomaterials. We investigated the effect of surface hydrophobicity on haemostatic activation in vitro, using five polyetherurethanes of varying surface hydrophobicity (C94, C74, C54 and C34), C94 the most, and C34, the least hydrophobic, and compared them with a commercial standard pellethane. Sterilised sacks were filled with heparinised blood, rotated at 37 degrees C for 24 h and sequential samples collected into 0.103 M sodium citrate. Thrombin generation measured by thrombin-antithrombin III complexes showed a difference between the polymers at 3 h through to 6 h (P < 0.05), C94 showing the least activation and C34 the most. Factor XIIa and D-dimer levels increased between 12 (P < 0.05) and 24 h (P < 0.01) for all polyetherurethanes. The ratio of soft:hard segments (which determine hydrophobicity) of the polyetherurethanes showed a direct relationship with the degree of activation of coagulation and fibrinolysis. There was no significant increase in monocyte tissue factor expression at 5 and 105 min. Platelet function as measured by whole blood platelet aggregation showed a reduction with pellethane and C94 after 1 h using collagen, with no changes for C34, Altering surface hydrophobicity has diverse effects on haemostatic pathways, with the most hydrophobic surfaces causing least activation of coagulation but most activation of platelets.
authors.affiliation: Department of Cardiothoracic Surgery, Imperial College School of Medicine, Harefield Hospital, Harefield, Middlesex. beverly.hunt@harefield.nthames.nhs.uk
authors.forename: B J
authors.initials: BJ
authors.lastname: Hunt
authors.forename: R
authors.initials: R
authors.lastname: Parratt
authors.forename: M
authors.initials: M
authors.lastname: Cable
authors.forename: D
authors.initials: D
authors.lastname: Finch
authors.forename: M
authors.initials: M
authors.lastname: Yacoub
mesh_terms: D000328:Adult; D001672:Biocompatible Materials; D001777:Blood Coagulation; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D005342:Fibrinolysis; D005434:Flow Cytometry; D006801:Humans; D006860:Hydrogen Bonding; D066298:In Vitro Techniques; D008297:Male; D015539:Platelet Activation; D011108:Polymers; D011140:Polyurethanes; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D005338:Fibrin Fibrinogen Degradation Products; D011108:Polymers; D011140:Polyurethanes; C044690:polyetherurethane urea