Keratocyte activation and apoptosis in transplanted human corneas in a xenograft model.
OBJECTIVE
To study keratocyte activation and cellular apoptosis in transplanted human corneas during the early postoperative period.


METHODS
Ten human donor corneas preserved for 6 days at 4 degrees C were transplanted into the eyes of 10 adult cats. After confocal and specular microscopy in vivo 1 week after keratoplasty, the cats were killed, and the fixed corneas were examined by TUNEL assay and by scanning (SEM) and transmission electron microscopy (TEM).


RESULTS
Abnormal keratocytes, in which portions of cell bodies and processes as well as nuclei were visible, were present in all corneas and occupied the anterior 16 to 562 microm of the stroma. By TEM in the same corneas, these abnormalities represented keratocytes that were activated to a repair phenotype. Only 0% to 1% of all corneal cells were apoptotic by TUNEL assay, except for the donor keratocytes near the wound, where 7% were apoptotic. The midstromal keratocyte density was decreased at 13,936 +/- 5,910 cells/mm(3) (mean +/- SD), and the endothelial cell density was 2,298 +/- 688 cells/mm(2), representing an endothelial cell loss of 7% +/- 16%.


CONCLUSIONS
Substantial keratocyte activation and low levels of cellular apoptosis occur 1 week after human corneal transplantation. The human-to-cat xenograft model of corneal transplantation demonstrated endothelial cell loss and other clinical findings similar to human allografts. The model will be useful for preclinical testing of new methods of long-term corneal preservation and of donor endothelial cell augmentation, as well as the study of human corneal wound healing and keratocyte replacement during the early postoperative period.
Ohno
Kenji
K
Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota 55905, USA.
Mitooka
Katsuya
K
Nelson
Leif R
LR
Hodge
David O
DO
Bourne
William M
WM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D017209:Apoptosis; D002415:Cats; D002452:Cell Count; D003315:Cornea / Q000473:pathology* / Q000601:surgery; D003319:Corneal Stroma / Q000473:pathology / Q000648:ultrastructure; D015925:Cryopreservation; D005347:Fibroblasts / Q000473:pathology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D015948:Keratoplasty, Penetrating / Q000473:pathology*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D023421:Models, Animal; D009926:Organ Preservation; D014183:Transplantation, Heterologous / Q000473:pathology*