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Biosynthetic bacterial cellulose graft as arteriovenous fistula ??? a complement to existing synthetic grafts

Abstract

Johan Magnusson, Katarina Björses, Jan Holst, Martin Malina, Karolina Helczynska

Introduction: There is an increasing need for vascular prosthesis in dialysis medicine for the construction of arteriovenous (AV)-fistulas for dialysis access. The aims of this study were; a) to develop and validate a new experimental AV-fistula model for larger animals using grafts of bacterial cellulose (BC) between the common carotid artery and the external jugular vein; b) to observe the immediate and intermediate properties (macroscopic and angiographic patency and the macro- and micro thrombogenicity) of the grafts. Materials and Methods: As graftmaterial bacterial cellulose was used, produced around a preformed scaffold. Bacterial cellulose (BC) is a material produced by the bacteria acetobacter xylinum. A pilotstudy was conducted on 6 pigs to validate the animalmodel and the new graftmaterial. In the following survival study a BC-graft AV-fistula was constructed in 15 pigs. Results: In the pilot study, 5 out of 6 animals had a patent AV-fistula 4 hours after implantation. In the survival study, after 4 (n3) and 8 (n10) weeks an angiography was performed prior to explantation of the BC-graft. All grafts were occluded with a presumed platelet plug. We conducted an additional acute patch-test comparing the BC and expanded PolyTetraFluoroEthylene. A patch of BC and ePTFE was applied to the right and left common femoral artery respectively. At explantation three hours later, all BC-patches showed a thin gel like layer, most likely consisting of platelets, throughout the whole surface while the ePTFE-patch showed no, or minimal, signs of platelet adhesions. Conclusion: Theoretically the cellulose might be similar to autologous veins considering risk of infections and thrombogenicity. The animal model and the graft material showed good potential in the pilot study. The survival study was discouraging with the reason for occlusion still to be explained. Bacterial cellulose has a good potential but further development and studies need to be performed.

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