Phosphorylcholine coating of ePTFE reduces platelet deposition and neointimal hyperplasia in arteriovenous grafts

In an attempt to reduce platelet deposition and inhibit neointimal hyperplasia, we evaluated the effect of coating expanded polytetrafluoroethylene (ePTFE) grafts with phosphorylcholine (PC), a lipid found in animal cell membranes, in a dog model of femoral arteriovenous (AV) grafts. Eight mongrel dogs underwent placement of a PC-coated femoral AV graft on one side and an untreated control graft on the contralateral side. Platelet deposition was measured by autologous ¹¹¹Indium-labeling and scintillation camera imaging analysis. Platelet deposition on the PC-coated grafts at 30 and 90 min. was 9.32 ± 4.35 x 10⁹ and 10.00 ± 4.38 x 10⁹, respectively, as compared with 10.26 ± 4.36 x 10⁹ and 11.64 ± 5.08 x 10⁹ platelet deposition on control grafts (P < 0.05). All grafts were patent at 4 weeks. There was a significant reduction of neointimal area at both arterial (0.07 ± 0.05 mm²) and venous (0.18 ± 0.09 mm²) anastomoses in the treated grafts as compared with arterial (0.15 ± 0.05 mm²) and venous (0.43 ± 0.22 mm²) anastomoses in the control grafts (P < 0.05). In addition, neointimal cell proliferation assayed by bromodeoxyuridine (BrdU) incorporation was reduced in both arterial (2.05 ± 0.81%) and venous (3.25 ± 0.17%) anastomoses of treated grafts compared with arterial (3.12 ± 1.23%) and venous (5.36 ± 1.18%) anastomoses of control grafts (P < 0.05). These data demonstrated that PC coating of ePTFE grafts significantly reduced platelet deposition, anastomotic neointimal hyperplasia, and neointimal cell proliferation in a dog model of AV grafts. This may represent a new strategy for prolonging hemodialysis graft patency.