title: [The collagen of the restenosis post angioplasty with stent: Is its origin in intima or adventitia?].
abstract: BACKGROUND
  Restenosis post stenting is due to the deposit of extracellular matrix, mainly collagen in the neointima. Controversy exists regarding if collagen is generated locally or by immigration from the adventitia.
  
  
  OBJECTIVE
  To study the fibrocellular response after stent implantation in rabbit iliac arteries. To observe, by immunohistochemistry and in situ hybridization, if collagen type I mRNA is expressed in the neointima, in the media or in the adventitia.
  
  
  METHODS
  Thirty eight white rabbits (New Zealand) of 4 kg received an hypercholesterolemic diet during 1 month. After this period, in all but 6 of them, an angioplasty with stent implantation was performed via right carotid artery in both iliac arteries, using a 1:1.3 relationship regarding the reference vessel. Angiograms were performed at day 0, 4, 21, and 40, followed by paraffin fixation of the injured segments, immunohistochemistry for alpha-actin and in situ hybridization to detect procollagen type I (alpha 1R1) mRNA.
  
  
  RESULTS
  No hybridization was observed in non injured arteries or at day 0 (n = 6). Expression of alpha 1R1 mRNA was observed in the neointima starting at day 4 after stenting (n = 8). At day 21 (n = 8) hybridization of procollagen type I was not only observed in the neointima, but also in the media, which became equally intense in both areas. At day 40 (n = 6) hybridization was observed similarly in the media and adventitia.
  
  
  CONCLUSIONS
  In this model, hybridization of procollagen type I started in the neointima, then involved the media and finally the adventitia. This finding might be useful for designing therapies to be delivered locally at the end of an angioplasty to prevent collagen deposition in the neointima.
authors.affiliation: Departamento de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile. eguarda@med.puc.cl
authors.forename: E
authors.initials: E
authors.lastname: Guarda
authors.forename: A
authors.initials: A
authors.lastname: Fajuri
authors.forename: A
authors.initials: A
authors.lastname: Martínez
authors.forename: E
authors.initials: E
authors.lastname: Marchant
authors.forename: A
authors.initials: A
authors.lastname: Vecchiola
authors.forename: E
authors.initials: E
authors.lastname: Valenzuela
authors.forename: R
authors.initials: R
authors.lastname: Lazen
mesh_terms: D000800:Angioplasty, Balloon; D000818:Animals; D024042:Collagen Type I / Q000032:analysis*; D006083:Graft Occlusion, Vascular / Q000378:metabolism* / Q000473:pathology; D007083:Iliac Artery / Q000378:metabolism* / Q000601:surgery; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D011347:Procollagen / Q000032:analysis*; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D015607:Stents; D017539:Tunica Intima / Q000378:metabolism* / Q000473:pathology
chemical_list: D024042:Collagen Type I; D011347:Procollagen; D012333:RNA, Messenger