Figure 1.

H₂O₂-induced oxidative stress reduces human mesenchymal stem cell (hMSC) viability by inducing mitochondrial dysfunction. (A) MTT assay was used to assess the viability of hMSCs treated with 200 μM H₂O₂ and that of untreated hMSCs. Values represent the mean ± SEM. * p < 0.05 or ** p < 0.01 vs. control. (B) Transmission electron microscopy (TEM) was used to evaluate mitochondrial morphology in hMSCs treated for 24 h with H₂O₂ (200 μM) and in untreated hMSCs. Scale bar = 500 nm. (C) Quantitative analyses of morphometric data and percentages of abnormal mitochondria showing swelling and severely disrupted cristae. Images were obtained using TEM. Values represent the mean ± SEM. ** p < 0.01 vs. control. (D) Tetramethylrhodamine, ethyl ester (TMRE)-positive hMSCs, with and without treatment using H₂O₂ (200 μM), were quantified via fluorescence-activated cell sorting (FACS). Values represent the mean ± SEM. ** p < 0.01 vs. control. (E) MitoSOX-positive hMSCs with and without treatment using H₂O₂ (200 μM) were quantified via FACS. Values represent the mean ± SEM. ** p < 0.01 vs. control.