Vascular response to coronary artery stenting in mature and juvenile swine ★

PurposeThe objective of this study was to investigate potential differences in vascular response to stenting of coronary arteries with bare metal (BMS) and drug-eluting (DES) stents in juvenile vs. mature swine.Methods and materialsTwenty-one mature (>3 years) and 22 juvenile (6-9 months) Yucatan swine were implanted with 3×12-mm XIENCE V DES and ML VISION BMS in coronary arteries. After 7 and 28 days, vessels were analyzed using light microscopy (n=5–7) and confocal and scanning electron microscopy (n=5–10). Messenger RNA expression levels of inflammatory and endothelial gene markers were tested from stented tissue at 7 and 28 days (n=3). A 2 × 2 analysis of variance followed by t tests compared treatment and/or age effects.ResultsNo age differences in neointimal area and percentage stenosis were measured. Juvenile swine exhibited increased fibrin scores compared to mature swine (2.6±0.5 vs. 2.2±0.5, P<.05) at 7 days, with no age-related difference at 28 days. At 7 days, significant increases in para-strut inflammation (P<.01) and in VCAM-1, ICAM-1, CD40 and MCP-1 gene expression (P<.05) were observed in mature swine, but differences were largely resolved by 28 days. DES exhibited less endothelial coverage than BMS at 7 days, but this difference was abrogated by 28 days, with no difference between age groups.ConclusionsOur results indicate that mature swine exhibited an increased foreign body response compared to mature swine at 7 and 28 days following stenting that may indicate marginal delays in resolution of foreign body response in aged populations. These differences are unlikely to affect methodologies for preclinical stent safety evaluations.