**4. Conclusions and further perspectives**

Polyester and polyether urethane structures with improved bulk and surface characteristics by blending with small amount of biocompatible cellulose derivative, HPC, are screened for long-time functional integration. The stability of the pH value of biological media and the ratio of adsorbed albumin and fibrinogen from blood plasma were found to be the most valuable screening criteria to evaluate the blood-interface functionality, but not only. These criteria could provide information on material capacity to keep stability of the main body balances (oxidant/antioxidant, haemostasis/haemolysis) that are responsible for material acceptance in the early phase, followed by structural and functional integration in the later stages. These characteristics together with other important material properties as surface neutral charge and desired porous structure are keys points for good results expectance as was demonstrated. Another PU characteristic highlighted in our study was washability for potentially proinflammatory compounds removal. Due to interconnected mechanisms of thrombosis and inflammation, even haemocompatible PU, but with chronic prolonged inflammatory capacity (through itself or some released compound) will certainly get to fail its haemocompatibility *in vivo*. From this point of view we demonstrate an acceptable stability of some PU membrane by autoclaving and long-time watering in biological buffers. Further studies are necessary on extended classes of polyurethanes in the aim to prepare and keep ready to use pre-equilibrated and safe PUs for medical applications.
