title: Analysis of telomere lengths in human corneal endothelial cells from donors of different ages.
abstract: OBJECTIVE
  To investigate the telomere hypothesis of cellular aging as the mechanism for cell cycle arrest in normal human corneal endothelium.
  
  
  METHODS
  The corneal endothelium and epithelium from 21 human corneas 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, HinfI, was run on 0.7% agarose gels, probed with radiolabeled (AATCCC)4, and exposed to a phosphor screen. The length of the terminal restriction fragment (TRF) was determined by densitometry.
  
  
  RESULTS
  The cells of the corneal endothelium had TRF lengths ranging from 11.0 to 14.0 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 epithelial cells from human donors nor the transformed pre-immortalized human endothelial cells showed evidence of telomerase activity.
  
  
  CONCLUSIONS
  Human corneal endothelial cells have long telomeres throughout life. Their limited replicative ability does not appear to result from critically short telomere lengths.
authors.affiliation: Department of Ophthalmology, Mayo Clinic Rochester, Minnesota 55905, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Egan
authors.forename: I
authors.initials: I
authors.lastname: Savre-Train
authors.forename: J W
authors.initials: JW
authors.lastname: Shay
authors.forename: S E
authors.initials: SE
authors.lastname: Wilson
authors.forename: W M
authors.initials: WM
authors.lastname: Bourne
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002453:Cell Cycle / Q000502:physiology; D016922:Cellular Senescence / Q000502:physiology; D004247:DNA / Q000032:analysis*; D004587:Electrophoresis, Agar Gel; D004728:Endothelium, Corneal / Q000502:physiology*; D019573:Epithelium, Corneal / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016615:Telomere / Q000235:genetics / Q000502:physiology*; D014019:Tissue Donors
chemical_list: D004247:DNA