Dose-Dependent Modulation of Endothelial Wound-Closure Dynamics by Water-Infused Labrador Tea: Acute Exposure and Preconditioning Followed by Hydrogen Peroxide Challenge

This project investigates how a traditional water-infused preparation of Rhododendron groenlandicum (Labrador tea) influences endothelial wound-closure dynamics in EA.hy926 endothelial cells. Using in vitro scratch (wound-healing) assays, endothelial repair was examined under two experimental conditions: acute exposure to increasing concentrations of Labrador tea under basal conditions, and repeated preconditioning with the same concentration range followed by a uniform hydrogen peroxide–induced oxidative challenge. Wound closure was quantified over time using time-resolved imaging, and percent gap closure was analyzed using linear mixed-effects models to account for repeated measurements within biological replicates. Across both experimental designs, endothelial wound closure progressed robustly over time, but closure dynamics were strongly dependent on treatment concentration and time. Higher concentrations, particularly 2.5%, were consistently associated with delayed closure at later stages of repair, while lower to intermediate concentrations displayed closure trajectories broadly comparable to controls. These findings demonstrate that a traditional water infusion can reshape endothelial repair behavior in a dose- and time-dependent manner, without producing uniform pro-migratory effects. The study highlights the importance of exposure history and time-resolved analysis when evaluating complex plant-based preparations in endothelial models, and cautions against relying solely on endpoint measurements to infer functional benefit.