Sex Chromosome Analysis of Postmortem Corneal Endothelium after Sex-Mismatch Descemet Membrane Endothelial Keratoplasty

Purpose: To identify the origin of corneal endothelial cells (host or donor) present on grafts at various time points after Descemet membrane endothelial keratoplasty (DMEK), using fluorescence in situ hybridization (FISH) of sex chromosomes on post mortem corneas with sex mismatch between the donor and host. Methods: Corneoscleral buttons of 6 post mortem DMEK eyes of 4 patients, operated for Fuchs endothelial dystrophy, with an average postoperative time of 2.6 (±1.8) years (range, 7 months-4.5 years), of 2.5 (±1.7) years (range, 7 months-4 years), were processed for FISH detection of XX (female) or XY (male)-labeling signals in corneal endothelial cells in the central area of the DMEK graft. Two male patients underwent bilateral DMEK with grafts from female donors, and 2 female patients underwent unilateral DMEK and received a graft from a male donor. Results: FISH consistently showed the presence of donor endothelial cells across the graft area, with signaling of sex chromosomes opposite to the sex of the host. Conclusions: Donor endothelial cells may survive up to 4.5 years after DMEK. If so, the lower incidence of allograft rejection in DMEK may not be explained by early host cell replacement. Potential host cell migration may be limited by donor/recipient cell-cell contact inhibition.