Biocompatibility of phosphorylcholine coated stents in normal porcine coronary arteries

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% v 92%, 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.