97th DOG Annual Meeting 1999
ANALYSIS OF CELL REPLACEMENT IN SEX-MISMATCHED HUMAN CORNEAL TRANSPLANTS BY FLUORESCENCE IN SITU HYBRIDIZATION OF THE SEX-CHROMOSOMES
The fate of the cells of corneal transplants has been controversial from the early days of keratoplasty. Various methods such as radiolabeling of donor cells or Barr-body analysis have been used to clarify the issue. However, the question whether the transplanted cells are replaced or survive remains unsolved.
Material and methods:At first, we developed an optimized protocol for the fluorescence in situ hybridization (FISH) of the X- and Y-chromosomes in 34 eye globes. We then applied the technique in paraffin sections of explanted sex-mismatched corneal transplants to distinguish between host and donor cells. Fourteen sex-mismatched cases with various explantation reasons and different postoperative time intervals ranging from 11 months to 30 years were analysed.
Results: We found that all cell types, including epithelium, keratocytes, and endothelial donor cells were replaced in most cases as early as 1 year after transplantation. In three cases, however, up to 26% of donor keratocytes were still detected up to 4.5 years after transplantation demonstrating a certain individual variability in the process of replacement.
Conclusions: Our results explain the phenomenon of recurrences of corneal dystrophies in the graft, the significant postoperative decline of the endothelial cell density, the fact that typical graft rejections usually take place within 1-2 years postoperatively and that relatively late rejections can occur in rare cases probably due to some surviving stromal keratocytes.
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