Why are telomeres important? Cells stop duplicating when telomeres become too short. Therefore telomere length is considered to be an excellent biomarker of tissue renewal capacity and, consequently, of aging. Telomeres progressively shorten with increasing age as a consequence of cumulative cycles of cell division that are required for tissue repair and regeneration. Telomere-shortening can be seen as a programmed aging ‘disease’, and could be cured by lengthening telomeres via telomerase induction.