Immunohistofluorescence analysis of myofibroblast transdifferentiation in human corneas with bullous keratopathy.

PURPOSE: To detect the transdifferentiation of keratocytes into myofibroblasts in human corneas with bullous keratopathy and to examine the relation of such transdifferentiation to the clinical course of the disease. METHODS: Twenty patients with bullous keratopathy who underwent penetrating keratoplasty were enrolled in the study. Corneal buttons collected during surgery were examined for expression of α-smooth muscle actin (αSMA) by immunoblot analysis and by immunofluorescence analysis of whole-mount preparations. The course of bullous keratopathy was evaluated from clinical charts. RESULTS: Immunoblot analysis revealed a marked increase in αSMA expression in some corneas affected by bullous keratopathy. Immunofluorescence analysis revealed that αSMA was expressed in myofibroblastic cells in the stroma of 10 of the 20 corneas examined. Expression of αSMA was detected in subjects with a clinical history of corneal epithelial erosion from 12 months after the onset of clinical stromal edema. In contrast, in subjects without a clinical history of epithelial erosion, αSMA expression was not detected until at least 27 months after the onset of stromal edema. The incidence of αSMA expression in stromal cells was not significantly associated with topical steroid administration. CONCLUSIONS: Transdifferentiation of keratocytes into myofibroblasts was observed in human corneas affected by bullous keratopathy. Such transdifferentiation occurred earlier after the onset of stromal edema in patients with a clinical history of epithelial erosion than in those without such a history.