Endothelial cell recovery, acute thrombogenicity, and monocyte adhesion and activation on fluorinated copolymer and phosphorylcholine polymer stent coatings

This study compares the effects of two polymers currently being marketed on commercially available drug-eluting stents, PVDF-HFP fluorinated copolymer (FP) and phosphorylcholine polymer (PC), on re-endothelialization, acute thrombogenicity, and monocyte adhesion and activity. Rabbit iliac arteries were implanted with cobalt–chromium stents coated with FP or PC polymer (without drug) and assessed for endothelialization at 14 days by confocal and scanning electron microscopy (SEM). Endothelialization was equivalent and near complete for FP and PC polymer-coated stents (>80% by SEM). Acute thrombogenicity was assessed in a Chandler loop model using porcine blood. Thrombus adherence was similar for both polymers as assessed by clot weight, thrombin–antithrombin III complex, and lactate dehydrogenase expression. In vitro cell adhesion assays were performed on FP and PC polymer-coated glass coupon surfaces using HUVECs, HCAECs, and THP-1 monocytes. The number of ECs adhered to FP and control surfaces were equivalent and significantly greater than on PC surfaces (p < 0.05). There were no differences in THP-1 monocyte adhesion and cytokine (MCP-1, RANTES, IL-6, MIP-1α, MIP-1β, G-CSF) expression. The data suggests that biological responses to both FP and PC polymer are similar, with no mechanistic indication that these polymers would be causative factors for delayed vessel healing in an acute timeframe.