I.L. Valuev, L.V. Vanchugova, G.A. Sytov, L.I. Valuev

The new approach to increase the thromboresistance of polymeric materials by modification of their surface by biospecific ligands, which can interact with plasminogen from the blood is offered. The polyethylene, polystyrene, polyurethanes and polydimethylsiloxane were used as initial polymers. N_Ɛ-acryloyl - or a N_Ɛ-methacryloyl-L-lysine were used as biospecific ligands. The modified polymers were synthesized by radiation graft copolymerization of N_Ɛ-acryloyl - or a N_Ɛ-methacryloyl-L-lysine and unsaturated hydrophilic monomer (acrylamide or N-vinylpyrrolidone) on a polymer surface. In in vitro experiments it was shown that the contact of modified materials with the blood leads to the selective sorption on the surface of plasminogen, which autocatalytic turns in plasmin. The modification of polymers results in to the decrease of surface density of adhered platelets, to the increase of time of a clots formation on a polymer surface, to the decrease of rate constant of activation of complement system. The high thromboresistance of modified polymers was confirmed also by the results of in vivo experiments. Modified polyethyleneterephtalate vascular grafts were implanted into the caudal vein of a dog where the blood flow is very slow and there is high tendency for thrombosis. The vascular grafts were patent within the times of observation up to one month. The unmodified prostheses were entirely clotted within the first 3-5 days