We have recently shown that the in vitro differentiation of human mesenchymal stem cells (hMSCs) was accompanied by an increased sensitivity toward apoptosis; however, the mechanism responsible for this shift is not known. Here, we show that the repair of DNA double-strand breaks (DSBs) was more rapid in undifferentiated hMSCs than in differentiated osteoblasts by quantification of the disappearance of γ-H2AX foci in the nuclei after γ-irradiation-induced DNA damage. In addition, there was a marked and prolonged increase in the level of nuclear Ku70 and an increased phosphorylation of DNA-PKcs. This was accompanied by an augmentation in the phosphorylation of ATM in hMSCs post-irradiation suggesting the nonhomologous end joining repair mechanism. However, when hMSCs were induced to differentiate along the osteogenic or adipogenic pathways; irradiation of these cells caused an expeditious and robust cell death, which was primarily apoptotic. This was in sharp contrast to undifferentiated hMSCs, which were highly resistant to irradiation and/or temozolomide-induced DSBs. In addition, we observed a 95% recovery from DSB in these cells. Our results suggest that apoptosis and DNA repair are major safeguard mechanisms in the control of hMSCs differentiation after DNA damage. © AlphaMed Press.
CITATION STYLE
Oliver, L., Hue, E., Séry, Q., Lafargue, A., Pecqueur, C., Paris, F., & Vallette, F. M. (2013). Differentiation-related response to DNA breaks in human mesenchymal stem cells. Stem Cells, 31(4), 800–807. https://doi.org/10.1002/stem.1336
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