%0 Journal Article
%T Obstacles in Haemocompatibility Testing
%A W. van Oeveren
%J Scientifica
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/392584
%X ISO 10993-4 is an international standard describing the methods of testing of medical devices for interactions with blood for regulatory purpose. The complexity of blood responses to biomaterial surfaces and the variability of blood functions in different individuals and species pose difficulties in standardisation. Moreover, in vivo or in vitro testing, as well as the clinical relevance of certain findings, is still matter of debate. This review deals with the major remaining problems, including a brief explanation of surface interactions with blood, the current ISO 10993 requirements for testing, and the role of in vitro test models. The literature is reviewed on anticoagulation, shear rate, blood-air interfaces, incubation time, and the importance of evaluation of the surface area after blood contact. Two test categories deserve further attention: complement and platelet function, including the effects on platelets from adhesion proteins, venipuncture, and animal derived- blood. The material properties, hydrophilicity, and roughness, as well as reference materials, are discussed. Finally this review calls for completing the acceptance criteria in the ISO standard based on a panel of test results. 1. Introduction Application of biomaterials in direct blood contact results in activation of the blood coagulation system and in an inflammatory reaction. These responses of blood are due to the natural response of the host defence mechanism against foreign surfaces. Inadequate control by natural inhibitors results in pathological processes, such as microthrombi generation or thrombosis, bleeding complications, haemodynamic instability, fever, edema, and organ damage. These adverse events become manifest during prolonged and intensive foreign material contact with vascular implants and extracorporeal blood circulation [1¨C7]. Despite their small surface area, coronary stents impose an ongoing risk for thrombosis by 1% per year [8]. A major difference between blood contacting and tissue implants is that blood might continue to be activated, despite a covering layer of proteins and cells, whereas implants in tissue become encapsulated and thus neutralised within weeks. It is hard to speculate on a direct relation with haemocompatibility, but consensus exists about the important role of poor haemocompatibility in direct and sustained adverse reactions. This review will deal with some of the remaining important practical aspects and problems of haemocompatibility testing. Adequate positive reference materials are warranted and acceptance criteria for all aspects
%U http://www.hindawi.com/journals/scientifica/2013/392584/