The Distribution of Stem Cell Marker P63 in Ethanol-Induced Corneal Injury in Adult Male Albino Rat. Histological and Immunohistochemical Study

Introduction: P63 is one of many markers postulated for epithelial stem cells. Corneal epithelial cells migrate from periphery to the centre of cornea. The mechanisms that control their proliferation and differentiation remain limited. Aim of the Work: This work was planned to study the distribution of P63 in ethanol-induced corneal injury. Materials and Methods: This study was performed on 25 adult male albino rats. Animals were randomly divided into five groups. Both eyes of control, group I were treated with sterile saline 0.9%. Corneal injury was induced in the remaining groups by topical application of ethanol 20%. Animals were sacrificed as follows groups II,III,IV,V at 0,1,2,3 days after injury. All sections were stained with H E for histological study and P63 immunostaining . Moreover statistical analysis was done to measure the mean area percent of P63 immunostaining and the mean thickness of the corneal epithelium. Results: In group II separation of corneal epithelium as well as of stromal fibers was noted. At corneoscleral junction mononuclear infiltration and congested blood vessels were seen. In groupIII flat nuclei at the corneal surface were recorded. In group IV epithelium starts to regenerate. Group V exhibited completely regenerated epithelium in central cornea. Immunohistochemical study in control group showed negative P63 immunostaining in central cornea, while it was positive in basal cells of the limbus. In group II same findings were recorded with few positive limbal stromal cells. In group III few P63 positive cells were detected in the central cornea. In groups IV V the nuclei of regenerating epithelium were positive for P63.The mean area % of P63 positive cells increased from the limbus to the center of injured cornea to reach its peak at day 3 when healing of cornea occurred. Concerning thickness of corneal epithelium, groupV showed significant increase in comparison to group IV. Conclusion: The immunoexpression of P63 correlated with corneal epithelial cells regeneration which postulated a role of p63 positive cells in their proliferation and differentiation.