In the past few years, the specific role of telomerase in stem cells started to be figured out, especially in hematopoietic stem cells (HSC) [2][3], skin stem cells [4] and neuronal stem cells (NSC) [5]. For instance, it was observed that in men and mice, HSC lose telomeric DNA with age. This progressive shortening of the telomeres seems to act as a barrier to HSC development, limiting the regeneration of hematopoietic cells and the renewal of all blood cells [2].

Regarding skin stem cells, the role of telomere length and activity was always established from TERC-/- mice models, mice lacking the TERC gene. In those mice, telomere shortening is associated to a decrease of skin stem cells function and their mobilization (proliferation and migration) is inhibited outside of the hair follicles [4]. Those mice with critical length telomeres have issues with skin and hair regeneation, which signals skin stem cells malfunction. Besides skin cells, TERC-/- mice have exhibited the atrophy of other tissues that usually benefit from high cellular renewal, such as bone marrow, gut and testicular cells. This atrophy is linked to very short telomeres [1]. All these observations confirm that telomeres and telomerase play a role in preserving stem cells and the good health of tissues in the body.