Phosphorylcholine coating of ePTFE grafts reduces neointimal hyperplasia in canine model

This study attempts to prevent neointimal hyperplasia by coating the graft luminal surface with a derivative of phosphorylcholine (PC), thereby providing a biocompatible surface with the assumption of limiting pannus tissue ingrowth from the graft anastomoses. Bilateral carotid artery bypass grafts were placed in six dogs using expanded polytetrafluoroethylene (ePTFE). In each animal, one carotid arterial-arterial conduit was constructed using a graft having a PC coating over the entire luminal surface of the graft. On the contralateral side, uncoated graft served as a control. The processed specimens were analyzed for graft neointimal area and neointimal thickness. Cell proliferation was assessed by staining for bromodeoxyuridine (BrdU) incorporation. All grafts were patent except one control graft that was occluded at 4 weeks. There was a significant reduction in the anastomotic graft neointimal area between the treated and control groups (0.27 ± 0.17 mm² versus 0.53 ± 0.13 mm², respectively; p = 0.008). Furthermore, the BrdU labeling index in the graft neointimal tissues was significantly smaller (p < 0.001) in the treated group (2.64 ± 0.77%) as compared with the control group (5.07 ± 0.83%). These data demonstrate that PC coating of ePTFE significantly reduces graft neointimal hyperplasia and cell proliferation in a canine carotid artery bypass model. The application of PC within the ePTFE graft effectively blocks tissue ingrowth from the adjacent native vessel, thereby preserving the anastomosis luminal diameter.