title: Polymer-free biolimus a9-coated stent demonstrates more sustained intimal inhibition, improved healing, and reduced inflammation compared with a polymer-coated sirolimus-eluting cypher stent in a porcine model.
abstract: BACKGROUND
  Drug-eluting stents effectively reduce restenosis but may increase late thrombosis and delayed restenosis. Persistent polymer, the drug, or a combination of both could be responsible. Local delivery of Biolimus A9, a rapamycin derivative, from a polymer-free BioFreedom stent (Biosensors International) may prevent these complications.
  
  
  RESULTS
  We compared high-dose (HD) (225 microg/14 mm Biolimus A9) and low-dose (LD) (112 microg/14 mm Biolimus A9) BioFreedom stents with a polymer-coated sirolimus-eluting Cypher stent (SES) and a bare-metal stent (BMS) at 28 days and 180 days in an overstretch coronary mini-swine model with histomorphometric and histological analysis. At 28 days, there was a reduction in neointimal proliferation by HD, LD, and SES compared with BMS (neointimal thickness: HD, 0.080+/-0.032; LD, 0.085+/-0.038; SES, 0.064+/-0.037; BMS, 0.19+/-0.111 mm; P<0.001; BMS > HD/LD/SES). At 180 days, both BioFreedom stents were associated with reduced neointimal proliferation, whereas SES exhibited increased neointima (neointimal thickness: HD, 0.12+/-0.034; LD, 0.10+/-0.040; SES, 0.20+/-0.111; BMS, 0.17+/-0.099 mm; P<0.001; SES > HD/LD; BMS > LD). At 180 days, BioFreedom stents showed decreased fibrin and inflammation, including granuloma and giant cells, compared with SES.
  
  
  CONCLUSIONS
  The polymer-free Biolimus A9-coated stent demonstrates equivalent early and superior late reduction of intimal proliferation compared with SES in a porcine model. After implantation of BioFreedom stent, delayed arterial healing was minimal, and there was no increased inflammation at 180 days compared with SES implantation. The use of polymer-free stents may have a potential long-term benefit over traditional polymeric-coated drug-eluting stents.
authors.affiliation: Heart Institute, Cedars-Sinai Medical Center, 8631 W. Third Street, Los Angeles, CA 90048, USA.
authors.forename: Norio
authors.initials: N
authors.lastname: Tada
authors.forename: Renu
authors.initials: R
authors.lastname: Virmani
authors.forename: Gordon
authors.initials: G
authors.lastname: Grant
authors.forename: Lauren
authors.initials: L
authors.lastname: Bartlett
authors.forename: Alexander
authors.initials: A
authors.lastname: Black
authors.forename: Claudia
authors.initials: C
authors.lastname: Clavijo
authors.forename: Uwe
authors.initials: U
authors.lastname: Christians
authors.forename: Ron
authors.initials: R
authors.lastname: Betts
authors.forename: Doug
authors.initials: D
authors.lastname: Savage
authors.forename: Shih-Horng
authors.initials: SH
authors.lastname: Su
authors.forename: John
authors.initials: J
authors.lastname: Shulze
authors.forename: Saibal
authors.initials: S
authors.lastname: Kar
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D023903:Coronary Restenosis / Q000628:therapy*; D054855:Drug-Eluting Stents; D005337:Fibrin / Q000378:metabolism; D015726:Giant Cells / Q000187:drug effects* / Q000473:pathology; D006099:Granuloma; D007249:Inflammation; D020123:Sirolimus / Q000008:administration & dosage* / Q000031:analogs & derivatives; D013552:Swine; D013556:Swine, Miniature; D017539:Tunica Intima / Q000187:drug effects* / Q000254:growth & development / Q000473:pathology / Q000601:surgery; D014945:Wound Healing / Q000187:drug effects
chemical_list: D005337:Fibrin; D020123:Sirolimus