Telomere shortening in kidneys with age

The histology and function of the kidney deteriorates with age and age-rela ted diseases, but the mechanisms involved in renal aging are not known. In vitro studies suggest that telomere shortening is important in replicative senescence, and is accelerated by stresses that increase replication. This study explored the relationship between age and telomere length in surgical samples from 24 human kidneys, which were either histologically normal (17 ) or displayed histologic abnormalities (7). Telomere loss was assessed by two independent methods: Southern blotting of terminal restriction fragment s (TRF) and slot blotting using telomere-specific probes. The results of th ese methods correlated with each other. The mean TRF length determined by S outhern blotting in cortex was about 12 kb pairs (kbp) in infancy and was s horter in older kidneys. The slope of the regression line was about 0.029 k bp (0.24%, P = 0.023) per year. Telomere DNA loss in cortex by the slot blo t method was 0.25% per year (P = 0.011). By both methods, the telomere loss in medulla was not significant and was less than in cortex. Comparisons of TRF length from 20 paired samples from cortex and medulla showed that TRF was greater in cortex than medulla, with the differences being greater in y oung kidneys and lessening with age due to telomere loss in cortex. These f indings indicate that telomeres shorten in an age-dependent manner in the k idney, either due to developmental factors or aging, particularly in renal cortex.