The replicative senescent mesenchymal stem / stromal cells defect in DNA damage response and anti-oxidative capacity

Area of Science:

• Stem cell biology
• Aging research
• Genomic stability

Background:

• Mesenchymal stem/stromal cells (MSCs) are limited in clinical use by replicative senescence and malignant transformation.
• Genomic instability, linked to aging and tumorigenesis, arises from abnormal DNA damage response.
• The impact of aging on DNA damage response in MSCs remains largely unknown.

Purpose of the Study:

• To investigate the DNA damage response in aged, senescent human bone marrow-derived MSCs (sMSCs).
• To compare the DNA damage response of sMSCs with early-passage MSCs.
• To elucidate the mechanisms underlying impaired DNA repair and antioxidant capacity in aging MSCs.

Main Methods:

• Characterization of replicative senescent MSCs (sMSCs) via proliferation rate, senescence-associated β-galactosidase activity, P53, and P16 expression.
• Assessment of sMSC sensitivity to oxidative stress (hydrogen peroxide) and DNA double-strand breaks (bleomycin).
• Evaluation of DNA damage response using comet assays, γH2AX foci, reactive oxygen species detection, and gene expression analysis of antioxidant and DNA repair genes.

Main Results:

• Senescent MSCs exhibited reduced proliferation, increased senescence markers, and heightened sensitivity to oxidative stress and DNA damage agents.
• sMSCs demonstrated attenuated antioxidant and DNA repair capabilities compared to early-passage MSCs.
• Downregulation of key antioxidant (Cu/Zn-SOD, GPX, CAT) and DNA repair genes (OGG1, XRCC1, Ku70, BRCA2, XRCC4) was observed in sMSCs.

Conclusions:

• MSC aging is intrinsically linked to a diminished DNA repair and antioxidant capacity.
• Impaired DNA damage response and reduced protective mechanisms in aged MSCs contribute to genomic instability.
• These findings highlight critical challenges for the clinical application of aged MSCs and suggest potential therapeutic targets.