ANALYSIS OF TELOMERE LENGTHS IN HUMAN CORNEAL ENDOTHELIAL-CELLS FROM DONORS OF DIFFERENT AGES

PURPOSE. To investigate the telomere hypothesis of cellular aging as t he mechanism for cell cycle arrest in normal human corneal endothelium . METHODS. The corneal endothelium and epithelium from 21 human cornea s from 13 donors 5 weeks to 84 years of age were dissected and frozen at -70 degrees C. Purified DNA, digested with the restriction enzyme, Hinfl, was run on 0.7% agarose gels, probed with radiolabelled (AATCCC )(4), and exposed to a phosphor screen. The length of the terminal res triction fragment (TRF) was determined by densitometry. RESULTS. The c ells of the corneal endothelium had TRF lengths ranging from 11.0 to 1 4.0 kbp (mean, 12.2 +/- 0.9). Corneal epithelial specimens showed TRF lengths that were always less than (mean, 10.4 +/- 1.0; range 9.0-12.0 ) the corresponding endothelial TRF lengths. Human corneal endothelial cells, transformed with human papillomavirus type 16 oncogenes E6 and E7, showed decreasing TRF lengths from 11 kbp at population doubling level (PDL) 15 to 9.5 kbp at PDL 73. Neither the endothelial and epith elial cells front human donors nor the transformed pre-immortalized hu man endothelial cells showed evidence of telomerase activity. CONCLUSI ONS. Human corneal endothelial cells have long telomeres throughout li fe, Their limited replicative ability does not appear to result from c ritically short telomere lengths.