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Background First generation drug-eluting stents (DESs) were based on 316L stainless steel and coated with a permanent polymer.The vessel wall of these DESs was inflammatory and late in-stent thrombosis was reported.Hence,cobalt chromium based DES coated with a bioabsorbable polymer was an alternate choice.Methods Cobalt chromium based DES with bioabsorbable polymer (Simrex stent) as well as control stents (Polymer stent and EXCELTM stent) were implanted into porcine arteries.At a designated time,angiography,quantitative coronary angiography (QCA) analysis,histomorphometry,and electron-microscopical follow-up were performed.Results A total of 98 stents of all the three groups were harvested.At week 24,percent diameter stenosis (％DS),late loss (LL),and percent area stenosis (％AS) of Simrex was (12.9±0.4)％,(0.35±0.02) mm,and (24.5±4.2)％,respectively,without significant difference in comparison to commercialized EXCELTM stent.Slight inflammatory reaction was seen around the stent strut of Simrex,just as in the other two groups.Electron-microscopical follow-up suggested that it might take 4-12 weeks for Simrex to complete its re-endothelialization process.Conclusions Cobalt chromium based,bioabsorbable polymer coated sirolimus-eluting stent showed excellent biocompatibility.During 24 weeks observation in porcine model,it was proved that this novel DES system successfully inhibited neointima hyperplasia and decreased in-stent stenosis.It is feasible to launch a clinical evaluation to improve the current prognosis of DES implantation.