Real-time monitoring of oxidative injury of vascular endothelial cells and protective effect of quercetin using quartz crystal microbalance

Abstract

The adhesion, spreading, and proliferation of human umbilical vein endothelial cell line (HUVEC-C) cells, on a gold electrode were monitored using quartz crystal microbalance (QCM) measurements. The viscodensity effect caused by the normal action of the cells led to a decrease of the resonant frequency and increase of the motional resistance. The oxidative injury of HUVEC-C cells appeared immediately with the addition of H₂O₂, exhibiting the decline of cellular spreading area and cell coverage on the electrode surface and resulting in inverted QCM responses. The injured extent of the cells was found to be related to the content of H₂O₂. It is found that 0.05 mM quercetin added beforehand in the growth medium could remove completely the oxidative action of 1.0 mM H₂O₂. Quercetin with increased dosage still exerted a partial protective effect on HUVEC-C cells against oxidative injury induced by 2.5 mM H₂O₂. The microscope observations, electrochemical measurements, and MTT analysis validate the QCM assay results, indicating that quercetin is a valuable flavonoid anti-oxidant in the precaution and treatment for the oxidative injury of vascular endothelium.

Graphical Abstract

Upper part: Microscope images (×400) of 7.5×10⁴ HUVEC-C cells adhered to the substrate at 48 h in the presence of H₂O₂. Middle part: Real-time Δf ₀ and ΔR ₁ responses to the addition of 7.5×10⁴ HUVEC-C cells onto QCM gold electrode in the presence of H₂O₂ added at 24 h after the introduction of the cells. Lower part: Microscope images (×400) of 7.5×10⁴ HUVEC-C cells adhered to the substrate at 48 h in the presence of quercetin added at 18 h and H₂O₂ added at 24 h after the introduction of the cells

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