Determining the effect of the WNT/b‐catenin pathway on the ischemic blood‐brain barrier in vitro and in vivo

Abstract

The blood‐brain barrier (BBB) is a selectively permeable barrier made up of tight junctions formed by endothelial cells that separates the circulating blood from the brain extracellular fluid. The primary function of the BBB is to limit the movement of xenobiotics from the blood to the brain. In the event of an ischemic stroke, the BBB opens allowing water and ions to enter the brain, leading to excitotoxicity and edema formation. Targeting such opening of the barrier following ischemic stroke has become a focus in current stroke studies. It has been shown that the Wnt/b‐catenin pathway is important for barrier formation during embryonic development, therefore, we hypothesized that activation of this pathway following ischemic stroke would attenuate barrier dysfunction. Brain microvascular endothelial cells (BMECs) derived from iPSCs were cultured and placed in ischemic stress for 6hrs, followed by an 18‐hour period of re‐oxygenation. Wnt small molecule activators (CHIR99021 and SB‐216763) and inhibitors (XAV939, IWP‐4, IWR‐1) were introduced at different time points of differentiation, during ischemia, and during re‐oxygenation. Transendothelial Electrical Resistance (TEER) and permeability were performed to assess barrier integrity following re‐oxygenation. For in vivo studies, C57BL mice were subjected to one‐hour ischemia by MCAO. At the time of re‐oxygenation, mice were dosed with CHIR99021 (IP; 30mg/kg). 24‐hours post‐MCAO, TTC staining on brains was performed to determine infarct size and edema ratio. The results of the in vitro studies have shown that activation of the Wnt pathway during re‐oxygenation results in increased barrier function, suggesting that the Wnt pathway is a potential target for post‐stroke therapy.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.