Telomere shortening leads to the induction of DNA damage signaling, which has been associated with aging and stem cell decline. In this study, the authors used a cytokine array to help determine that telomere dysfunction impaired mesenchymal progenitor cell function, reduced the capacity of bone marrow stromal cells to maintain functional HSCs, and increased the expression of various cytokines, including granulocyte colony-stimulating factor (G-CSF). These cell-extrinsic alterations of the environment contributed to the decline in adult stem cell function during aging.

Ju, Zhenyu, et al. "Telomere dysfunction induces environmental alterations limiting hematopoietic stem cell function and engraftment." Nature medicine 13.6 (2007): 742.
https://www.ncbi.nlm.nih.gov/pubmed/17486088