Stem cells have trouble assuming a specialized identity if their telomeres, the protective caps on the ends of their chromosomes, are short.

Pluripotent stem cells can become any cell type in the body, and are known to require long telomeres to grow normally. A group led by Lea Harrington, formerly at the University of Edinburgh, UK, reports that telomeres are also important for stem cells to differentiate into other cell types. They found that mouse embryonic stem cells with experimentally shortened telomeres did not differentiate stably, and that the pluripotency gene Nanog, which is normally silenced during differentiation, was abnormally active in these cells. In addition, the chemical modifications to DNA that normally stabilize differentiation were disrupted throughout the genome.

Telomere length might also have a role in differentiation of cancer stem cells in the body, the authors suggest.

Cell Stem Cell 12, 479–486 (2013)