Immunohistochemical Study of Apoptosis of Lens Epithelial Cells in Human and Diabetic Rat Cataracts

We performed terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assays on capsulotomy specimens (53 patients, 68 eyes) from patients who had undergone cataract surgery, and on the epithelium of diabetic cataracts in rats (72 rats, 144 eyes). An animal model of diabetic cataracts was prepared by injection of streptozo-tocin in 3-week-old rats. The specimens of rats were also examined using the proliferating cell nuclear antigen (PCNA) immunohistochemical staining method. Results: Although some TUNEL-positive cells were detected in capsulotomy specimens, we recognized little correlation between their distribution and the morphological classification of the cataracts. In the animal model of diabetic cataracts, TUNEL-positive cells were seen around the regions of accumulated epithelial cells. In the accumulated regions, PCNA-labeled cells undergoing DNA synthesis were also detected. Conclusions: These results suggest the possibility that apoptosis occurs in human lens epi-thelial cells. Apoptosis and proliferation of lens epithelial cells may be induced by factors such as hyperglycemia