Long-Term Phenotypic Study after Allogeneic Cultivated Corneal Limbal Epithelial Transplantation for Severe Ocular Surface Diseases

Purpose: To determine the long-term epithelial lineage of origin of surgically removed grafts after allogeneic cultivated corneal limbal epithelial transplantation (CLET). Design: Interventional case reports. Participants: We studied 2 eyes from 2 patients with total corneal stem cell destruction; 1 eye was from a patient with Stevens-Johnson syndrome and 1 eye had sustained chemical injury. Methods: Allogeneic cultivated corneal limbal epithelial sheets on human amniotic membrane (AM) were transplanted onto the ocular surface. Regrafting (1 eye, 42 months later) or penetrating keratoplasty (1 eye, 75 months later) were performed after the initial transplantation procedure for further visual rehabilitation. Main Outcome Measures: The excised grafts were subjected to clinical evaluation and to light-and transmission electron microscopy (TEM) examination and to immunohistochemical analysis. Results: In clinically conjunctival grafts, TEM and immunohistochemical analysis disclosed only small areas where the original cultivated corneal epithelial cells persisted. Neighboring conjunctival epithelial cells had apparently invaded a large portion of the corneal surface (keratin 3/12(-), Muc5ac(+)). In clinically corneal grafts, transplanted allogeneic cultivated corneal epithelial cells clearly survived for a long period of time (keratin 3/12(+), Muc5ac(-)); there was no infiltration by inflammatory cells, nor was there dissolution of the AM substrate. Conclusions: We theorize that the process of graft opacification after allogeneic CLET is responsible for the loss of transplanted cultivated corneal epithelial cells and that this is followed by conjunctival cell invasion onto the corneal surface. The results of this study confirmed that in the clinically evaluated corneal graft, transplanted cultivated corneal epithelial cells indeed survived for a long period of time on the corneal surface and maintained ocular surface integrity, even though the transplanted cells were allogeneic.