title: Colonic mucosal biopsies obtained during confocal endomicroscopy are pre-stained with fluorescein in vivo and are suitable for histologic evaluation.
abstract: OBJECTIVE
  Confocal laser endomicroscopy (CLE) with intravenous infusion of fluorescein allows noninvasive, real-time in vivo visualization of gastrointestinal mucosa at ~ × 1000 magnification ("virtual biopsy"). Conventional biopsies obtained during these procedures serve as the reference and established diagnostic standard. The aim of the present study was to assess whether the standard histologic biopsies that are obtained during CLE retain fluorescein in the tissues and allow the visualization of mucosal structures without any additional staining.
  
  
  METHODS
  CLE optical imaging of the mucosa was performed in 16 patients who were undergoing CLE colonoscopy. Standard conventional biopsies were also obtained from both normal colonic mucosa and colonic polyps. De-paraffinized mucosal sections were examined under a fluorescence microscope for the presence and distribution of fluorescein, and then underwent immunostaining for expression of vascular endothelial growth factor (VEGF).
  
  
  RESULTS
  Standard mucosal biopsy sections from patients undergoing CLE displayed a strong fluorescence and showed well-delineated mucosal structures. In colonic adenomas, there was a 4.6-fold increased vascular permeability compared with normal mucosa (P<0.001), indicated by fluorescein leakage to the extravascular space. Immunostaining demonstrated an aberrantly increased expression of VEGF in the epithelium of colonic adenomas but not in the epithelium of normal mucosa or hyperplastic polyps.
  
  
  CONCLUSIONS
  This study shows for the first time that standard colonic biopsies obtained during CLE retain fluorescein, show excellent delineation of mucosal structures without additional staining, allow the evaluation of mucosal microvasculature and vascular permeability, and are suitable for immunostaining.
authors.affiliation: Institut des Maladies de l'Appareil Digestif - INSERM U913, CIC 04 et Service d'Hépato-Gastroentérologie, Hôtel Dieu, CHU de Nantes, France.
authors.forename: E
authors.initials: E
authors.lastname: Coron
authors.forename: J F
authors.initials: JF
authors.lastname: Mosnier
authors.forename: A
authors.initials: A
authors.lastname: Ahluwalia
authors.forename: M
authors.initials: M
authors.lastname: Le Rhun
authors.forename: J P
authors.initials: JP
authors.lastname: Galmiche
authors.forename: A S
authors.initials: AS
authors.lastname: Tarnawski
authors.forename: T
authors.initials: T
authors.lastname: Matysiak-Budnik
mesh_terms: D000236:Adenoma / Q000378:metabolism / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D001706:Biopsy / Q000379:methods; D003106:Colon / Q000378:metabolism / Q000473:pathology*; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D003111:Colonic Polyps / Q000378:metabolism / Q000473:pathology*; D003113:Colonoscopy; D005240:Feasibility Studies; D005260:Female; D019793:Fluorescein; D005456:Fluorescent Dyes; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology*; D008297:Male; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D011446:Prospective Studies; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D005456:Fluorescent Dyes; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D019793:Fluorescein