Shear-induced endothelial cell tight junctions, which cannot be achieved in the Transwell® model, are easily achieved in the SynBBB assay using fluid perfusion. Formation of tight changes can be measured using biochemical or electrical analysis (assessing changes in electrical resistance) with the SynVivo Cell Impedance Analyzer.

Primary endothelial cells are cultured in the vascular channel under physiological fluid flow. Cells are stained for tight junction markers highlighting the increase under fluid flow compared to static conditions. The Cell Impedance Analyzer system is used to measure increases in Ohmic resistance (TEER), associated with the formation of tight junctions.

Interactions between brain tissue cells and endothelial cells are readily visualized in the SynBBB assay. Transwell models do not allow real-time visualization of these cellular interactions, which are critical for understanding of the physiological environment.

Endothelial cells are cultured under flow in the vascular channel, and the tissue chamber is cultured with primary brain cells, such as astrocytes. Increases in Ohmic resistance across the barrier, measured with the Cell Impedance Analyzer, are associated with tight junction formation across the BBB. Endothelial cells co-cultured with astrocytes form significantly tighter cell junctions compared to mono-cultured endothelial cells.

Unlike BBB models which are arranged in top to bottom architecture (i.e., Transwell), small molecule transport can be assessed and quantified in real-time across the SynBBB system due to its side-by-side architecture.

A fluorescently-labeled drug molecule of interest is perfused through the vascular channels at physiological  flow rate. Real-time videos are acquired and analyzed to calculate the rate of permeability into the tissue chamber. Different rates of permeability is observed across the BBB due to tight junctions of endothelial cells.