Persistence of transplanted oral mucosal epithelial cells in human cornea.

Purpose: To determine the expression of differentiation and progenitor cell markers in corneal tissues that previously underwent autologous cultivated oral mucosal epithelial transplantation (COMET).
Methods: Four eyes from three alkaline-injured patients and one thermally injured patient underwent COMET to promote re-epithelialization or corneal reconstruction. Between 10 and 22 months (mean, 14.2 +/- 5.5 months [SD]) after COMET, the corneal tissues were obtained after penetrating keratoplasty (n = 1) or autologous limbal transplantation (n = 3). Immunoconfocal microscopy for keratin (K)3, -12, -4, -13, and -8; connexin (Cx)43; MUC5AC; laminin-5; pan-p63; ABCG2; and p75 was performed in those specimens as well as in the oral mucosa and cultivated oral mucosal epithelial cells (OMECs).
Results: All four specimens were unanimously positive for K3, -4, and -13 but negative for K8 and MUC5AC, suggesting that the keratinocytes were oral mucosa-derived. However, peripheral K12 staining was positive only in patient 2, suggesting a mixed oral and corneal epithelium in that case. Cx43 staining in the basal epithelium was negative in patients 1, 2, and 3, but was positive in patient 4. Small, compact keratinocytes in the basal epithelium preferentially expressed pan-p63, ABCG2, and p75. Although the staining of pan-p63 and ABCG2 tended to be more than one layer, signal for p75 was consistently localized only to the basal layer.
Conclusions: The study demonstrated the persistence of transplanted OMECs in human corneas. In addition, small, compact cells in the basal epithelium preferentially expressed the keratinocyte stem/progenitor cell markers, which may be indicative of the engraftment of the progenitor cells after transplantation.