Alpha-ketoglutarate enhances adipose-derived stem cells survival in wound healing by hypoxia-inducible factor 1-alpha-mediated redox homeostasis and glycogen-dependent bioenergetics

Figure 6 Hypoxia-inducible factor 1-alpha promotes cell survival, burn wound healing, and angiogenesis in α-ketoglutarate-adipose-derived stem cells. A: Terminal deoxynucleotidyl transferase dUTP nick end labeling immunostaining at day 3 after cell implantation, with quantification of TUNEL+ cells; B: Ex vivo cell viability of CM-FDA-labeled cells 3 days after implantation. Viable cells are CM-FDA⁺AnxV-PI^-; C: Cell viability analysis on cells cultured in combined stress conditions [1% O₂, 1 mmol/L glucose, 12 mmol/L H₂O₂ (high H₂O₂)]. Viable cells are AnxV-PI^-; D and E: Ratio of glutathione to glutathione disulfide in in vivo implanted (D) or in vitro cultured (E) adipose-derived stem cells (ADSCs), α-ketoglutarate-ADSCs (αKG-ADSCs), and HIF-1α^KD αKG-ADSCs; F and G: In vivo intracellular reactive oxygen species levels in ADSCs, αKG-ADSCs, and HIF-1α^KD αKG-ADSCs (F) or in vitro cultured cells (G); H: Glycogen content of implanted ADSCs, αKG-ADSCs, and HIF-1α^KD αKG-ADSCs; I: Intracellular glycogen deposition determined after extraction from cells during normal culture conditions or glucose deprivation; J: Fold enrichment of HIF-1β binding to promoter regions of Ldh-a, Pdk1, Gls1, Gys1, and Pygl in ADSCs, αKG-ADSCs, and HIF-1α^KD αKG-ADSCs, as determined by chromatin immunoprecipitation followed by quantitative polymerase chain reaction; K: Hematoxylin-eosin staining of the mouse burn wounds treated with ADSCs, αKG-ADSCs, and HIF-1α^KD αKG-ADSCs. Data are presented with means ± SEM (^aP < 0.05, ^bP < 0.01). ADSCs: Adipose-derived stem cells; αKG-ADSCs: Alpha-ketoglutarate adipose-derived stem cells; TUNEL: Terminal deoxynucleotidyl transferase dUTP nick end labeling; GSH: Glutathione; GSSG: Glutathione disulfide; MFI: Mean fluorescent intensity; HIF-1α: Hypoxia-inducible factor 1-alpha.