Investigation of endotelization, bacterial contamination and biofilm creation in PTFE grafts with different internal surfaces

BACKGROUND: The expanded polytetrafluoroethylene (ePTFE) grafts are commonly employed in peripheral vascular surgery have and may have different internal surface coatings. Graft infection and graft thrombosis are two main complications of prosthetic graft bypass procedures and may cause high mortality and morbidity. The aim of our study is to investigate the effect of different prosthetic ePTFE graft coating methods on endothelialization, bacterial contamination, and biofilm formation. METHODS: Three different types of grafts were examined for biofilm formation and endothelization. ePTFE grafts without any coating and grafts with luminal surface coatings of either heparin or carbon were used and contaminated with Staphyloccocus Aureus strain.Christiansen method was used for biofilm detection. In addition, grafts with completed biofilm formation were assessed by scanning electron microscopy (SEM). Human umbilical vein endothelial cells (HUVEC) were used for the determination of endothelialization. After endothelial cell cultivation grafts were visualized under SEM and examined at six different times between the 3rd and 25th days after cultivation for the proliferation of endothelial cells. RESULTS: The spectrophotometric method was used to determine the biofilm formation on grafts and quantitative values were used to compare the intensity of biofilm formation on each graft type. The biofilm formation for heparin-coated grafts was found to be statistically significantly higher than the other two graft types (p <0.05). We observed that the number of microorganisms was increased in heparin-coated grafts under the SEM examination. The adherence of endothelial cells on carbon-coated grafts was found to be increased, in examinations performed at 15th, 20th and 25th days after endothelial seeding. Heparin-coated grafts were observed to contain fewer endothelial cells in comparison with the other graft types on each examination performed. CONCLUSION: Our in-vitro study has shown that heparin coating on the inner surface of the ePTFE graft increases the formation of biofilm as an adhesion factor for microorganisms and hinders endothelial cell proliferation and inner graft endothelialization. Keywords: ePTFE, heparin coated, carbon coated, biofilm, endothelialization, graft infection, graft endothelialization, HUVEC