Fig. 6: The outcomes of aging bone defect repair with the CSN@PHA-MBG scaffold.

Sequential fluorescence labelings of bone formation with calcein (green) and alizarin red S (red) (a) and the corresponding quantitative analysis of mineral apposition rate (b) (n = 8 biologically independent samples), histological examination of neo-tissues at the aging bone defect site after indicated treatments on day 14 and 28 (c), representative SRµCT images of neo-tissues at day 28 after control, PHA-MBG or CSN@PHA-MBG treatment (d) and the corresponding quantification of BV/TV (e), Tb.Th (f), and Tb.N (g) (n = 3 biologically independent samples), representative immunostaining images (h) and the corresponding quantification data (i) of p16 (red), Vpp3 (red), Osterix (white) and Emcn (green) expressions in neo-tissues on day 28 after indicated treatments (n = 4 biologically independent samples), illustration of the mechanism of hydrogen-mediated injured aging bone regeneration, where local and sustained H₂ release from the CSN@PHA-MBG scaffold remodeled the SME by inducing effective anti-inflammation (macrophage polarization) and universal anti-senescence, and consequently promoted MSCs recruitment and preserved their regenerative capability (j). BV/TV, the ratio of bone volume to total volume; Tb.N, trabecular number; Tb.Th, trabecular thickness. Data are means ± SD. P values were calculated by the Two-tailed unpaired Student’s t test method. b **p = 0.0040; e ***p = 0.0003; f *p = 0.0370; g *p = 0.0481; i **p = 0.0086 for p16, *p = 0.0317 for Vpp3; ns means no significant difference (p > 0.05). Source data are provided as a Source Data file.