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Total body irradiation causes long-term mouse BM injury via induction of HSC premature senescence in an Ink4a- and Arf-independent manner

Shao, L., Feng, W., Li, H. et al.

Exposure to total body irradiation (TBI) induces not only acute hematopoietic radiation syndrome but also long-term or residual bone marrow (BM) injury. This residual BM injury is mainly attributed to permanent damage to hematopoietic stem cells (HSCs), including impaired self-renewal, decreased long-term repopulating capacity, and myeloid skewing. These HSC defects were associated with significant increases in production of reactive oxygen species (ROS), expression of p16Ink4a (p16) and Arf mRNA, and senescence-associated β-galacotosidase (SA-β-gal) activity, but not with telomere shortening or increased apoptosis, suggesting that TBI induces residual BM injury via induction of HSC premature senescence. This suggestion is supported by the finding that SA-β-gal+ HSC-enriched LSK cells showed more pronounced defects in clonogenic activity in vitro and long-term engraftment after transplantation than SA-β-gal LSK cells isolated from irradiated mice. However, genetic deletion of p16 and/or Arf had no effect on TBI-induced residual BM suppression and HSC senescence, because HSCs from irradiated p16 and/or Arf knockout (KO) mice exhibited changes similar to those seen in HSCs from wild-type mice after exposure to TBI. These findings provide important new insights into the mechanism by which TBI causes long-term BM suppression (eg, via induction of premature senescence of HSCs in a p16-Arf–independent manner).

Citation

Shao, L., Feng, W., Li, H. et al. "Total body irradiation causes long-term mouse BM injury via induction of HSC premature senescence in an Ink4a- and Arf-independent manner" Blood (2014): 3,105–15