Protective Roles of Zinc and Selenium Against Oxidative Stress in Brain Endothelial Cells Under Shear Stress

Hypertension is a major risk factor for cerebrovascular diseases due to its damaging effects on the blood-brain barrier (BBB) and associated pathologies. Oxidative stress-induced endothelial damage plays a critical role in BBB disruption, potentially leading to cognitive impairment and neurodegeneration. In this study, we investigated the protective effects of two essential trace elements, zinc (Zn) and selenium (Se), against oxidative stress in human brain endothelial cells (HBCE5i) exposed to hypertensive shear stress. Using an innovative millifluidic system (LiveBox2), which allows for the precise simulation of continuous flow conditions, we replicated the hemodynamic forces associated with hypertension.

Cells were treated with ZnCl₂ (5-50 µM) or Na₂SeO₃ (50-500 nM) at concentrations selected based on previous studies and confirmed by cytotoxicity assays.

Our results demonstrated that shear stress significantly altered the localization of the tight junction protein zonula occludens-1 (ZO-1) and induced the nuclear translocation of the transcription factor NRF2, a hallmark of oxidative stress. Importantly, treatment with 10 µM ZnCl₂ preserved ZO-1 membrane localization and prevented NRF2 translocation, as confirmed by quantitative image analysis. In contrast, Na₂SeO₃ did not provide comparable protection, although modest improvements in ZO-1 localization were observed in some replicates.

We discuss potential reasons for selenium's limited efficacy, including differences in bioavailability and cellular uptake. Our findings underscore zinc's promising role as a neurovascular protector and suggest that further investigation into more complex in vitro models and in vivo studies is warranted.