Axion BioSystems' Maestro Z, TrayZ, ZHT, Pro, and Edge systems offer impedance-based cell analysis for real-time, continuous, label-free monitoring of your cells. Continuous data reveals the full time course of barrier disruption for a more complete picture without the time- and cost-intensive process of repeating multiple endpoint assays.
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Epithelial and endothelial cells form barriers in the body. The strength and integrity of these barriers can be assessed via measurements of the electrical resistance across the cell layer in vitro, called TEER (Trans-Epithelial Electrical Resistance Assay).
1:00: What is TEER
1:40: Plating cells on Maestro Z
2:00: Measuring frequencies of electrical resistance
2:50: TEER in disease modeling
TEER is often used with epithelial and endothelial cells in a monolayer as a strong indicator of cell barrier integrity and permeability. These indicators are often used in vitro with evaluating transport of drug chemicals or drug screening assays.
How does TEER work:
Impedance technology is used to measure TEER. A small AC current is passed from one electrode to another. TEER measures how much of this electrical signal is blocked by the cellular layer, thereby quantifying barrier integrity. Because impedance is non-invasive and label-free, the barrier can be continuously monitored for minutes, hours, or even days without disturbing the cellular biology.
How TEER is measured on a plate
Electrodes embedded in the cell culture substrate at the bottom of each well detect small changes in the impedance of current flow. Barriers, such as tight junctions between cells, resist current flow, leading to an increase in TEER measurements of barrier function.
Common biological models evaluated with TEER:
Blood-brain barrier
Gastrointestinal tract
Pulmonary models
Organ-on-a-chip
The biological models are often assessed with TEER in order to evaluate drug or chemical transport or diffusion.
Measuring frequencies of electrical resistance:
Measuring impedance at low frequency is highly sensitive to the intercellular barrier formed by tight junctions and the paracellular barrier formed by cell membranes. On the other hand, measurements at higher frequency can be used to quantify coverage of the well bottom. In other words, low frequencies are sensitive to “what” cells are there, whereas high frequencies are sensitive to “how many” cells are there.
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