<bold>The aim of the study.</bold> Assessment of dynamic changes in the expression of activators and inhibitors of coagulation and fibrinolysis in the neointima of polyester vascular grafts during their healing process.
<bold>Material and methods.</bold> The study was carried out on 18 dogs that underwent replacement of infrarenal abdominal aorta with a polyester DALLON - double velour prosthesis. Grafts were removed after 1, 4 and 12 months and fixed according to the AMeX method. Immunohistochemical labeling for tissue factor (TF), tissue factor pathway inhibitor (TFPI), tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA), plasminogen activator inhibitor type-1 (PAI-1), prothrombin activation fragment F1+2 (F1+2) and D-dimer (DD) was performed on the neointima of the grafts.
<bold>Results.</bold> TF expression did not demonstrate any significant differences in all study periods. TFPI expression appeared at 4 months and was increased at 12 months. Intensive F1+2 expression was shown at 1 month; its mild expression was still present in the following periods of the study. Plasminogen activators were demonstrated at 1 month and their expression was increased at 4 and 12 months, whereas weak expression of PAI-1 and DD was shown in all study periods.
<bold>Conclusions.</bold> High thrombotic potential of polyester vascular graft neointima is present in all periods of the graft healing process. Increasing TFPI and plasminogen activators expression in the late postoperative follow-up favors graft patency maintenance.