In vivo assessment of a novel Dacron surface with covalently bound recombinant hirudin

Prosthetic arterial graft surfaces are relatively thrombogenic and fail to heal with a cellular neointima. The goal of this study was to characterize the in vivo antithrombin properties of a novel Dacron surface with covalent ly linked recombinant hirudin (rHir) implanted in a canine thoracic aorta w ith high flow and shear rates. rHir was bound to a knitted Dacron patch using crosslinker-modified bovine serum albumin (BSA) as a basecoat protein. BSA was first reacted with the h eterobifunctional crosslinker, sulfo-SMCC, This BSA-SMCC complex was then b ound to the carboxylic acid groups of hydrolyzed Dacron patches using the c arbodiimide crosslinker, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydr ochloride. Iodinated, Traut's-modified rHir (I-125-rHir-SH) was then reacte d with the Dacron-BSA-SMCC surface, thereby covalently binding I-125-rHir. Graft segments were washed and sonicated to remove any nonspecifically boun d I-125-rHir. Dacron-BSA-SMCC-S-I-125-rHir patches (n = 5) and control Dacr on-BSA patches (n = 5) were implanted in series in the thoracic aortas of c anines. These patches were exposed to nonheparinized, arterial blood flow f or 2 hours. Patches were explanted and assessed for I-125-rHir loss. Antith rombin activity of explanted 1-cm(2) patch segments was evaluated using a c hromogenic assay with 1, 5, 10, 15 units of added thrombin. Light microscop y was performed to qualitatively examine the pseudointima. Two animals were excluded from the study owing to excessive bleeding throug h the knitted I-125- rHir patch. Comparison of preoperative and postoperati ve I-125-rHir gamma counts revealed an overall decrease of 20 +/- 5.4% over the period studied. Explanted I-125-rHir patch segments were able to inhib it 1, 5, and 7 NIHU of thrombin, demonstrating retained antithrombin activi ty. Gross and microscopic examination of the control and test Dacron surfac es showed marked differences. Dacron surfaces with covalently bound I-125-r Hir had no gross thrombus and a thin pseudointima of platelets and plasma p roteins. In contrast, the control patches had a thick pseudointima composed of fibrin-rich thrombus. rHir, covalently bound to Dacron patches, maintains its biologic activity a s well as prevents thrombus formation on the graft surface. This novel anti thrombin coating, by modifying the blood/ graft interface, may improve both short- and long-term patency in small-diameter prosthetic arterial grafts and has applications with respect to other implantable or indwelling biomat erials. Cardiovasc Pathol 1999;8:153-159 (C) 1999 by Elsevier Science Inc.