Background: Skin flap ischemia/reperfusion (IR) injury contributes to reducing the survival rate in flaps after grafting. Lysine demethylase 5B (KDM5B) plays a crucial role in epigenetic regulation both during normal development and carcinogenesis. Therefore, this study aims to investigate the precise role and underlying mechanism of KDM5B in the skin flap after IR injury.

Methods: An in vitro skin flap model was developed in oxygen-glucose deprivation/reoxygenation (OGD/R)-treated human umbilical vein endothelial cells (HUVECs), and the expression levels of KDM5B, AMP-activated protein kinase (AMPK), and Kruppel-like factor 2 (KLF2) were assessed using western blot and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses. Furthermore, cellular apoptosis rate, scratch wound healing, migration, and tube formation were assessed in treated HUVECs using flow cytometry, Transwell, and tube formation assays, respectively.

Results: KDM5B was downregulated in the skin flap after IR injury in vivo (p < 0.05). In vitro, KDM5B overexpression alleviated OGD/R-induced injury in HUVECs, as verified by the rescued cell viability (p < 0.05), reduced Lactate dehydrogenase (LDH) release (p < 0.05) and restored mitochondrial membrane potential (p < 0.05). Additionally, overexpression of KDM5B suppressed OGD/R-induced apoptosis (p < 0.05), enhanced cell migration (p < 0.05), and promoted tube formation (p < 0.05) in HUVECs. Mechanistically, KDM5B overexpression activated the AMPK/KLF2 signaling pathway, which was inhibited by OGD/R treatment (p < 0.05). The protective effects of KDM5B on apoptosis, migration, and tube formation were abolished by the AMPK inhibitor Compound C (p < 0.05). The in vivo experiments confirmed that KDM5B overexpression promoted skin flap survival (p < 0.05), reduced apoptosis (p < 0.05), and enhanced angiogenesis (p < 0.05).

Conclusion: This study is the first to demonstrate that KDM5B suppresses apoptosis and enhances migration and angiogenesis in the skin flap after IR injury through activation of the AMPK/KLF2 signaling pathway.