Stent-mediated methylprednisolone delivery reduces macrophage contents and in-stent neointimal formation

In Brief Objective Corticosteroids have a wide range of biological effects. Stent-based methylprednisolone delivery could effectively suppress peri-strut inflammation and neointima induced by a polymer matrix. We tested the safety and efficacy of local stent-mediated methylprednisolone delivery using a biological coating on in-stent neointimal formation in a porcine coronary stent model. Methods Stainless steel coronary stents were dip-coated in a biological polymer/ methylprednisolone solution, resulting in total load of 530 μg methylprednisolone per stent. In-vitro drug release was performed. Stainless steel bare stents, polymer-only and methylprednisolone-coated stents (MP) were implanted in coronary arteries of pigs with a stent/artery ratio of 1.2 : 1. Histopathologic evaluation, morphometry and immunohistochemistic staining were analyzed at 4-week follow-up. Results In-vitro drug release studies showed sustained release up to 10 weeks. In vivo the vascular response of polymer-only-coated stents was comparable with the bare stents. No increased peri-strut inflammation and neointimal hyperplasia were observed. The in-stent neointimal formation of methylprednisolone-coated stents was significantly reduced compared with the bare and polymer-only-coated stents (bare, 1.92±0.73; polymer-only, 2.14±1.50; MP, 1.01±0.47 mm2, P=0.019). The macrophage content of methylprednisolone-coated stents (bare, 30.74±48.67; polymer-only, 19.55±24.60; MP, 1.16±3.33/mm2, P=0.072) was dramatically decreased. However, there were no significant difference among the three group in terms of the proliferating cells expressed by proliferation cell nuclear antigens. Conclusion Stent-based local methylprednisolone delivery could effectively decrease both vascular macrophage infiltration and in-stent neointimal hyperplasia. Stent-based methylprednisolone delivery could suppress peristrut inflammation and neointima induced by a polymer matrix. In this study a biological coating was used for stent-based local methylprednisolone delivery. A good biocompatibility of the biological coating to arterial wall was observed. Local released methylprednisolone could effectively decrease the vascular macrophage infiltration and in-stent neointimal hyperplasia in a porcine coronary stent model.