title: Cellular effects of mitomycin-C on human corneas after photorefractive keratectomy.
abstract: OBJECTIVE
  To investigate the effects of mitomycin-C (MMC) on epithelial and keratocyte cell kinetics after photorefractive keratectomy (PRK) using an in vitro human cornea model.
  
  
  METHODS
  Department of Academic Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
  
  
  METHODS
  Twenty-four human eye-bank corneas were placed in a specially designed acrylic corneal holder and cultured using the air-interface organ culture technique for up to 4 weeks. The corneas were divided into 3 groups. Group 1 consisted of 8 human corneas that had -9.00 diopter (D) myopic PRK without MMC application. Group 2 consisted of 8 corneas that had -9.00 D PRK with MMC (0.2 microg/mL) application for 1 minute on the stromal surface after ablation. Group 3 consisted of 8 corneas that had -9.00 D PRK with 2-minute exposure to MMC (0.2 microg/mL). Temporal events in epithelial and keratocyte cell kinetics were evaluated using digital imaging, confocal microscopy, and light microscopy.
  
  
  RESULTS
  Epithelial latency was significantly delayed with MMC application in Groups 2 and 3 (P<.001). Epithelial migration was delayed in Group 3 (2-minute exposure) compared to migration in Group 2 (P<.04), with a consequent delay in epithelial closure (P<.001). Group 3 corneas had poorly differentiated epithelium that was significantly thinner than in Groups 1 and 2 (P<.0001). A significant delay in keratocyte regeneration occurred after MMC application (P<.0005). At 4 weeks, the anterior stromal cell density was significantly lower in Group 3 than Group 2 (P<.001). There were no significant differences in the mid- and posterior stromal keratocyte density between the groups.
  
  
  CONCLUSIONS
  Results suggest that epithelial healing after MMC is characterized by prolonged latency and decreased migration rate dependent on exposure time. Mitomycin C application did not result in increased loss of keratocytes, but it significantly delayed keratocyte repopulation in the anterior stroma. The use of MMC 0.2 microg/mL for 1 minute resulted in optimum modulation of healing characterized by reduced keratocyte activation with normal epithelial differentiation.
authors.affiliation: Department of Academic Ophthalmology, Rayne Institute, St Thomas' Hospital, London, UK. msrajan@tiscali.co.uk
authors.forename: Madhavan S
authors.initials: MS
authors.lastname: Rajan
authors.forename: David P S
authors.initials: DP
authors.lastname: O'Brart
authors.forename: Anne
authors.initials: A
authors.lastname: Patmore
authors.forename: John
authors.initials: J
authors.lastname: Marshall
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology*; D002465:Cell Movement; D003315:Cornea / Q000166:cytology / Q000187:drug effects* / Q000601:surgery*; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology; D006801:Humans; D054018:Lasers, Excimer; D018613:Microscopy, Confocal; D008875:Middle Aged; D016685:Mitomycin / Q000494:pharmacology*; D009216:Myopia / Q000601:surgery; D009924:Organ Culture Techniques; D018903:Photorefractive Keratectomy; D014019:Tissue Donors; D014945:Wound Healing
chemical_list: D000477:Alkylating Agents; D016685:Mitomycin