Abstract
Purpose: :
Mitomycin C (MMC) is used commonly in conjunction with various corneal and conjunctival surgeries to control excessive cell proliferation. However, it is not well understood how MMC affects the extravasation and the movement of polymorphonuclear leukocytes (PMNs) that appear frequently after surgery. The aim of this study was to determine whether MMC alters appearance and disappearance of PMNs in the corneal stroma, using an epithelial scrape injury model with the mouse eye.
Methods: :
Twenty mice underwent mechanical epithelium debridement in the central cornea with the assistance of 20% ethanol. After the scrape, the right eye received 0.02% MMC for one minute while the left eye received saline. Animals were sacrificed at 1, 2, 5, and 14 days after the surgery, and corneal whole mounts were prepared for histology. The epithelium was removed and the denuded stroma was stained with hematoxylin. PMN distribution was analyzed in digitized microscope images. Cell division in the cornea was determined by immunohistochemical detection of bromodeoxyuridine which was injected intraperitoneally 2 hours before sacrificing the mouse.
Results: :
Epithelial scrape injury triggered infiltration of PMNs into the anterior stroma of the injury site within 24 hours, by which time the epithelial opening was closed 80–100%. The majority of PMNs appeared to have originated from the limbal vasculature because tears did not contain an increased level of PMNs after injury. Most of the PMNs disappeared from the cornea by five days after injury. BrdU labeling demonstrated that keratocyte division was apparent in the injury area at 5 days but not at 2 days. This keratocyte division at 5 days was inhibited by the MMC treatment. An analysis of PMN distribution revealed that there was no clear difference between eyes treated with and without MMC at all time points.
Conclusions: :
An MMC treatment regimen that is common in clinical practice inhibits keratocyte proliferation during wound healing, but it does not affect PMN infiltration into the corneal stroma and subsequent movement toward the injury site, nor their disappearance from the stroma, in the mouse epithelial injury model.
Keywords: cornea: basic science • inflammation • wound healing