title: Transepithelial riboflavin/ultraviolet. a corneal cross-linking in keratoconus: morphologic studies on human corneas.
abstract: OBJECTIVE
  To evaluate histologic and molecular changes in human keratoconic corneas after the procedure of transepithelial collagen cross-linking (CXL), without the removal of corneal epithelium.
  
  
  METHODS
  Experimental laboratory investigation.
  
  
  METHODS
  Thirty corneal buttons were examined, 18 of which were from patients affected by severe keratoconus and submitted to penetrating keratoplasty (PK). Among these, 8 were analyzed without any treatment, 4 were treated with transepithelial CXL 2 hours before PK, and 6 were treated with transepithelial CXL 3 months before PK. Twelve normal corneal buttons from healthy donors were used as controls. The corneal buttons were then evaluated by hematoxylin-eosin staining and by immunostaining with markers of epithelial junction proteins (ß-catenin and connexin 43), of stromal keratocytes (CD34), of apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling [TUNEL] assay), and of collagen type I fibers.
  
  
  RESULTS
  The analysis of epithelial markers showed a clear defective expression in keratoconic corneas before and soon after the transepithelial CXL treatment, returning to normal in corneas analyzed 3 months after transepithelial CXL. The analysis of stroma components indicated a loss of keratocytes in the upper stroma of keratoconic corneas and a trend toward a normal situation 3 months after transepithelial CXL; similarly, collagen fibers appeared disorganized in keratoconus, while their pattern appears to be close to normal 3 months after treatment.
  
  
  CONCLUSIONS
  Histologic and immunohistochemical findings on human keratoconic corneas showed the presence of biochemical and morphologic alterations in the epithelium and the upper stroma that are significantly improved 3 months after transepithelial CXL. However, further studies are necessary to assess to what extent these results correlate with measurable biomechanical effects.
authors: Department of Surgery and Translational Medicine, Eye Clinic, University of Florence, Florence, Italy. Electronic address: rita.mencucci@unifi.it.
authors: Rita
authors: R
authors: Mencucci
authors: Iacopo
authors: I
authors: Paladini
authors: Erica
authors: E
authors: Sarchielli
authors: Eleonora
authors: E
authors: Favuzza
authors: Gabriella Barbara
authors: GB
authors: Vannelli
authors: Mirca
authors: M
authors: Marini
mesh_terms: D000328:Adult; D018952:Antigens, CD34 / Q000378:metabolism; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D018031:Connexin 43 / Q000378:metabolism; D003315:Cornea / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D003319:Corneal Stroma / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D019573:Epithelium, Corneal / Q000187:drug effects; D006801:Humans; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D007640:Keratoconus / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D015948:Keratoplasty, Penetrating; D008875:Middle Aged; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012256:Riboflavin / Q000627:therapeutic use*; D014466:Ultraviolet Rays; D055815:Young Adult; D051176:beta Catenin / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D015415:Biomarkers; D024042:Collagen Type I; D018031:Connexin 43; D003432:Cross-Linking Reagents; C500216:GJA1 protein, human; D017319:Photosensitizing Agents; D051176:beta Catenin; D012256:Riboflavin