Subendothelial pericytes in the intima of venous bypass grafts catalyze thromboembolic and atherosclerotic processes

Abstract

Objectivedeeper insight into the mechanisms of thrombotic and proliferative occlusion of coronary bypass grafts of venous origin and remedy. Common preparation and intraoperative storage of grafts in usual preservation solutions (such as saline) cause vast endothelial denudation (>50%) and exposure of newly detected subendothelial pericytes (P) of the intima. P express a high tissue factor concentration and form the prothrombinase complex (31±4 nmol Xa bzw. 5.7nmol ± 1.08 Prothrombin •min−1•10−6cells), thus catalysing rapid formation of fibrin thrombi. Following exposure to locally formed serum, P proliferate more rapidly (doubling time <18h). Attached platelets and leukocytes accelerate the procoagulatory and proliferative processes further, and endothelium‐dependent anticoagulatory activities are significantly abolished. In contrast, sealing venous grafts using a custom‐built injector system to prevent pressure artifacts during sealing and storage in a plasma derivative preserve graft endothelialization (>90%) with retention of typical anti‐thrombogenic endothelial activities. Given their general presence in the vascular intima, P may play a hitherto unrecognized role in many thrombotic and sclerotic illnesses. The optimized intraoperative handling techniques described can improve graft prognosis considerably. Supported by a grant of the Friedrich‐Baur‐Stiftung, Munich.