Tail tendon break time: a biomarker of aging?

Research has attempted to identify biomarkers of aging that are predictive of longevity and specific age-related changes during animal life span. Tail tendon break time (TTBT), one presumed biomarker, measures collagen cross-linking, known to increase with age. Significant differences in the rate of increase of TTBT with age have been reported between mouse strains and animal species. We measured both TTBT and longevity in C57BL/6J, DBA/2J, and 23 recombinant inbred (RI) strains (B×D RIs), with TTBT measured at 200, 500, and 800 days of age. Longevity demonstrated considerable variability among these strains (116-951 days). TTBT, also highly variable, increased significantly with age in both sexes and all genotypes. Neither TTBT nor its rate of change correlated significantly with life span. There were suggestive trends for rate of TTBT change to correlate with male longevity and strain longevity to correlate with female TTBT. We conclude that for the range of genetic variation found among these mouse genotypes, TTBT cannot be considered a robust biomarker of longevity.