Histopathological Analysis of Drug Eluting Stents in Porcine Coronary Restenosis Model

The aim of this study was to compare the two types of drug-eluting stents with histological analysis in porcine coronary restenosis model. Pigs were randomized into two groups in which the coronary arteries (12 pigs, 12 coronaries in each group) had either biolimus-eluting stent with biodegradable polymer (BPS) or sirolimus-eluting stent with durable polymer (DPS). Radiological analysis was performed pre-stent and post-stent implantation and histopathologic analysis was assessed at 28 days after stenting. Angiographic finding showed that the coronary artery was more narrowed by neointima proliferation in BPS compared to DPS. In histopathological analysis, the internal elastic lamina (IEL), lumen area, neointima area, percent area stenosis, and fibrin score were significantly different between the two groups ($5.1{\pm}0.79mm^2$, $2.8{\pm}0.85mm^2$, $2.3{\pm}0.75 mm^2$, $45.9{\pm}13.43%$, $0.4{\pm}0.79$ in BPS group vs. $4.2{\pm}0.93mm^2$, $3.0{\pm}0.90mm^2$, $1.2{\pm}0.67 mm^2$, $28.1{\pm}14.81%$, $2.0{\pm}0.93$ in DPS group, respectively). However, there was no significant difference in injury and inflammation score ($1.3{\pm}0.40$, $1.0{\pm}0.31$ in BPS group vs. $1.3{\pm}0.32$, $1.1{\pm}0.15$ in DPS group, respectively). Our study demonstrated that BPS was not effective to reduce neointima hyperplasia at 1 month after implantation of stents in porcine coronary artery. However, fibrin score of BPS which means delayed arterial healing is very lower than that of DPS.