The Concerted Action focused on the topic 'Problems related to Haemocompatibility'.
The collaboration project EUROBIOMAT -Haemocompatibility commenced with the collection of detailed descriptions of test methods developed or adapted in Europe, covering all aspects of haemocompatibility and biocompatibility of biomaterials according to the fundamental demands for their safe application like biofunctionality, thromboresistance, nontoxicity, biostability, mechanical strength, sterilizability. These test standards allowed for the first time the comparison of test results, by following the instructions of the experts and applying identical techniques. The outcome of this was the edition of a book of standards.
An expanding network of european test centres has been established in order to compare test results, to evaluate the limitations of individual test procedures and to qualify and certify biocompatible materials and surfaces. Approximately 28 European test centres are involved, each of them contributing a particular fragment of biomaterials testing. Candidate medical materials can be tested by an upgraded system of examinations through this network, and thereby the practical validity of new surfaces or surface modifications can be predicted at an early stage and with more certainty than previously.
Six different reference materials (tubes and sheets), all of them already in clinical use, were purchased and distributed to the collaborating centres. Each of these 6 materials was produced under identical conditions in medical grade quality from one single batch in different dimensions and in larger quantities in order to provide any new interested research centre with standard surfaces to control their test facilities.
New and better haemocompatible biomaterial surfaces have been developed as well as disposable polyvinyl chloride (PVC) tubes with alternative plasticisers with an essentially decreased migration rate and lower toxicity.
The radio frequency (RF) plasma-glow-discharge-polymerisation has been considered as the most advantageous physical technique to modify surfaces in order to realise highly thromboresistant biomaterials. EUROBIOMAT recommends this technique in particular because of the following;
conversion of low cost materials into high quality biocompatible materials;
independence of substrate type;
unlimited range of surface chemistry;
treatment of whole medical devices including sterilisation;
dry and rapid processing;
low toxicity of the surface coating due to leaching;
control of permeability;
coatings with excellent optical properties.
The demand for haemocompatibility is one of the basic factors for a safe and sufficient application of artificial surfaces being in contact with blood either permanently or temporarily. Thrombus formation and infarction of the capillary vascular system after blood material interaction as well as the activation of the complement system and the phenomenon of biodegradation are still unsolved problems. However, medical devices where large areas of such artificial surfaces contact the blood of patients are applied in enormous quantities.
In spite of the high significance of this branch of modern medicine and certainly spectacular success in therapy, organ support, and organ replacement, clearly specified criteria, guidelines and instructions for the design of devices and artificial blood contacting surfaces and their safe application do not yet exist. Standardised and generally accepted test procedures in order to quantify and validate precisely the events on the blood-material-interface were up to now not available. These circumstances limited a safe medical therapy as well as a more efficient development of new and better haemocompatible blood contacting polymeric surfaces.
Obviously, the missing success in the development of new and better haemocompatible biomaterials is due to one single reason: the absence of generally accepted and standardised test procedures to qualify blood contacting surfaces.