Mitochondrial Disruption: How Zoledronic Acid Compromises Vascular Endothelial Cells

Abstract

<p>Objectives: Zoledronic acid (Zol) is commonly used in the treatment of osteoporosis and significantly inhibits angiogenesis, a property thought to be a crucial factor in the development of medication-related osteonecrosis of the jaws (MRONJ). Vascular endothelial cells (VECs) are crucial for vascular homeostasis, relying on mitochondria for energy and signalling. However, the impact of Zol on VEC mitochondria remains unknown. This study aimed to investigate the effect of Zol on VEC mitochondrial function and explore the underlying mechanism.<br>Methods: The proliferation, migration and tube formation of VECs were detected by cell counting kit 8, transwell assay and tube formation assay. The level of cell apoptosis, mitochondrial-reactive oxygen species and mitochondrial membrane potential were analysed by flow cytometry. The expression level of vascular endothelial growth factor A (VEGFA), phosphatase and tensin homolog-induced putative kinase 1 (PINK1), B-cell lymphoma-2 interacting protein 3 (BNIP3), and FUN14 domain containing 1 (FUNDC1) was detected by western blot. The level of mitophagy was assessed by observing co-localization of autophagosomes through immunofluorescence.<br>Results: Zol inhibited proliferation, migration, tube formation and reduced the expression of VEGFA in VECs. Additionally, Zol was found to increase apoptosis and mitochondrial-reactive oxygen species, and decrease mitochondrial membrane potential in VECs revealed by flow cytometry. Immunofluorescence displayed that the co-localization level of mitochondria and autophagosome decreased in Zol-treated VECs. Western blot revealed that there was no significant change in PINK1 expression, while the expression levels of BNIP3 and FUNDC1 decreased in Zol-treated VECs.<br>Conclusions: Zol impaired biological function, induced apoptosis and caused mitochondrial dysfunction in VECs, thereby inhibiting angiogenesis. The effect may be associated with inhibition of mitophagy by Zol. Targeting mitochondrial dysfunction could enhance VEC function under Zol treatment, enabling safer clinical use of Zol and preventing the onset of MRONJ.</p>​​​​​​​