Endothelial ELABELA improves post-ischemic angiogenesis by upregulating VEGFR2 expression

Post-ischemic angiogenesis is critical for perfusion recovery and tissue repair. ELABELA (ELA) plays an essential role in embryonic heart development and vasculogenesis. However, the mechanism of ELA on post-ischemic angiogenesis is poorly characterized.

We first assessed ELA expression after hind limb ischemia (HLI) in mice. We then established a HLI model in tamoxifen-inducible endothelial-ELA-specific knockout mice (ELA^ECKO) and assessed the rate of perfusion recovery, capillary density, and VEGFR2 pathway. Knockdown of ELA with lentivirus or siRNA and exogenous addition of ELA peptides were employed to analyze the effects of ELA on angiogenic capacity and VEGFR2 pathway in endothelial cells in vitro. The serum levels of ELA in healthy people and patients with type 2 diabetes mellitus (T2DM) and diabetic foot ulcer (DFU) were detected by a commercial ELISA kit.

In murine HLI models, ELA was significantly up-regulated in the ischemic hindlimb. Endothelial-specific deletion of ELA impaired perfusion recovery and angiogenesis. In physiologic conditions, no significant difference in VEGFR2 expression was found between ELA^ECKO mice and ELA^WT mice. After ischemia, the expression of VEGFR2, p-VEGFR2, and p-AKT was significantly lower in ELA^ECKO mice than in ELA^WT mice. In cellular experiments, the knockdown of ELA inhibited endothelial cell proliferation and tube formation, and the addition of ELA peptides promoted proliferation and tube formation. Mechanistically, ELA upregulated the expression of VEGFR2, p-VEGFR2, and p-AKT in endothelial cells under hypoxic conditions. In clinical investigations, DFU patients had significantly lower serum levels of ELA compared to T2DM patients.

Our results indicated that endothelial ELA is a positive regulator of post-ischemic angiogenesis via upregulating VEGFR2 expression. Targeting ELA may be a potential therapeutic option for peripheral arterial diseases.