Fig. 4: CNPs protect against apoptosis by restoring the redox homeostasis.

a Flow cytometry results of HK-2 cells after treatment with vehicle and DDP with or without CNPs; cells were stained with Annexin V-FITC/PI. Representative images are shown. n = 3 independent experiments. b Proportion of normal, necrosis, early apoptosis, and late apoptosis in HK-2 cells. n = 3 independent experiments. c Western blot analysis of the cleaved PARP (clv-PARP) and cleaved caspase-3 (clv-caspase-3) levels in HK-2 cells after different treatments. GAPDH served as a loading control. n = 2 independent experiments. d Representative TUNEL staining images in kidneys. n = 3 independent mouse kidneys. Scale bar: 100 μm. The red dotted line indicates the boundary between the kidney edge and background, and the white dotted line represents the boundary between the renal cortex and the medulla. e Quantification of TUNEL positive cells in the respective groups. n = 3 independent mouse kidneys, P_(DDP) = 0.0015, P_{(0.5 CNPs)} = 0.0035, P_{(1.5 CNPs)} = 0.0016. f ROS content in HK-2 cells detected by flow cytometry analysis after different treatments. Representative images are shown. n = 3 independent experiments. g Statistical results of ROS level in HK-2 cells from each group. n = 3 independent experiments, P_(DDP) = 1.8E−06, P_(DDP+CNPs) = 4.5E−06. h, i Detection of SOD activities (h) and MDA levels (i) in HK-2 cells after different treatments. n = 3 independent experiments. In h, P_(DDP) = 0.0206, P_(DDP+CNPs) = 0.0233; in i, P_(DDP) = 0.0015, P_(DDP+CNPs)= 0.00297. j, k Relative mRNA expressions of antioxidant gene HO-1 (j) and pro-oxidant gene NOX2 (i) in the renal cortex of mice from each group. n = 3 independent experiments. In j, P_(DDP) = 0.00034, P_{(0.5 CNPs)} = 0.00016, P_{(1.5 CNPs)} = 3.2E−05; in k, P_(DDP) = 0.0026, P_{(1.5 CNPs)} = 0.0043. Data are presented as means ± SEM., *P < 0.05, **P < 0.01, ***P < 0.001, ^#P < 0.05, ^##P < 0.01, ^###P < 0.001; one-way ANOVA with multiple comparisons test. Source data are provided as a Source Data file.