PURPOSE. Severe destruction of the corneal limbus causes conjunctival invasion and subsequent visual loss. Limbal allograft transplantation (LAT) was recently proposed for the treatment of these disorders. However, whether the method functions as a stem cell transplantation of the corneal epithelium remains unclear. This study provided evidence that donor-derived corneal epithelial cells survive long after LAT.
METHODS. Epithelial cells on the paracentral cornea in patients who have undergone LAT were subjected to fluorescence in situ hybridization (FISH) and polymerase chain reaction restriction fragment length polymorphism (RFLP) analysis. X and Y chromosomes were detected using sex chromosome-specific probes in the FISH analysis, and HLA-DPB1 antigens were examined in the RFLP analysis. Eyes receiving conventional penetrating keratoplasty (PKP) served as controls.
RESULTS. Donor-derived epithelial cells were detected in three of five eyes (60.0%) in the FISH analysis and in seven of nine eyes (77.8%) in the RFLP analysis. Among these eyes, one and three eyes in the FISH and RFLP analysis, respectively, had both donor- and recipient-derived cells. In control PKP eyes, none of the eyes in the FISH analysis and one of eight eyes (12.5%) in the RFLP analysis had donor-derived cells.
CONCLUSIONS. These results suggest that donor-derived cells survive much longer after LAT than those after PKP, and that LAT may function as stem cell transplantation of the corneal epithelium.