Biocompatibility of phosphorylcholine coated stents in normal porcine coronary arteries

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Abstract
OBJECTIVE To improve the biocompatibility of stents using a phosphorylcholine coated stent as a form of biomimicry. INTERVENTIONS Implantation of phosphorylcholine coated (n = 20) and non-coated (n = 21) stents was performed in the coronary arteries of 25 pigs. The animals were killed after five days (n = 6), four weeks (n = 7), and 12 weeks (n = 8), and the vessels harvested for histology, scanning electron microscopy, and morphometry. MAIN OUTCOME MEASURES Stent performance was assessed by studying early endothelialisation, neointima formation, and vessel wall reaction to the synthetic coating. RESULTS Stent thrombosis did not occur in either group. Morphometry showed no significant differences between the two study groups at any time point. At five days both the coated and non-coated stents were equally well endothelialised (91% v92%, respectively). At four and 12 weeks there was no difference in intimal thickness between the coated and non-coated stents. Up to 12 weeks postimplant the phosphorylcholine coating was still discernible in the stent strut voids, and did not appear to elicit an adverse inflammatory response. CONCLUSION In this animal model the phosphorylcholine coating showed excellent blood and tissue compatibility, unlike a number of other polymers tested in a similar setting. Given that the coating was present up to 12 weeks postimplant with no adverse tissue reaction, it may be a potential candidate polymer for local drug delivery.