Understanding TEER: A Key Tool for Studying Barrier Integrity
Why Barrier Integrity Matters
Cell barriers, such as the intestinal epithelium, blood–brain barrier, or corneal endothelium, are critical for controlling what enters and exits tissues. A compromised barrier can lead to disease, while a strong barrier is essential for maintaining health.
Understanding how our body's protective barriers function is crucial for advancing treatments and developing new therapies. For researchers, accurately measuring barrier integrity is vital in fields ranging from drug development to disease modeling. One of the most important tools scientists use to study these barriers is TEER (Transepithelial Electrical Resistance or Transendothelial Electrical Resistance). This powerful measurement technique provides valuable insights into the integrity and function of cellular barriers that protect our organs and tissues. TEER is a gold-standard, non-invasive technique for quantifying the integrity and permeability of cell monolayers grown in culture.
What is TEER?
TEER is a quantitative measurement of the electrical resistance across a cellular monolayer. In simpler terms, it measures how well a layer of cells blocks the passage of ions and small molecules, essentially testing how "tight" the cellular barrier is. The measurement is expressed in ohms per square centimeter (Ω·cm²) and reflects the integrity of tight junctions between adjacent cells. In simple terms:
- High TEER values indicate tight junctions between cells and a well-formed, low-permeability barrier.
- Low TEER values suggest leaky or compromised barriers, where ions and molecules can pass more freely.
TEER measurements work on a fundamental principle of electrical resistance. Researchers typically grow cells on permeable supports or inserts. When cells form a monolayer with intact tight junctions, they create a barrier that restricts the movement of ions. This restriction increases electrical resistance across the cell layer. Electrodes placed above and below the cell monolayer apply a small current, and the resistance is measured. This resistance reflects how well the cell junctions block ion flow, serving as a proxy for barrier function.
The measurement process involves:
- Electrode Placement: Two electrodes are positioned on opposite sides of the cell monolayer, with one in the apical (top) chamber and one in the basolateral (bottom) chamber.
- Current Application: A small, alternating current is applied across the cell layer.
- Voltage Measurement: The voltage drop across the monolayer is measured.
- Resistance Calculation: Using Ohm's law (V = IR), the resistance is calculated and normalized for the surface area.
Why Use TEER?
The beauty of TEER is that it’s:
- Quantitative: Provides numerical data that can be tracked over time.
- Non-destructive: Unlike dye permeability assays, TEER doesn’t damage cells.
- Real-time: Measurements can be taken repeatedly during experiments to follow barrier development, drug response, or injury.
- Reproducible: Standardized protocols yield consistent results.
- Cost-effective: Relatively inexpensive compared to other barrier assessment methods.
- High throughput: Multiple samples can be measured quickly using an automated system like WPI’s EVOM™ Auto.
TEER primarily reflects the resistance of tight junctions between cells, cell membranes themselves, and the paracellular pathway (the space between cells). When tight junctions are well-formed and functional, they significantly increase the electrical resistance, resulting in higher TEER values.
WPI pioneered TEER measurement solutions with the EVOM™ series of manual and automated systems, as well as specialized electrodes designed for reproducibility and precision. These systems allow researchers to measure TEER in cell culture inserts of various sizes, track barrier formation over time, and compare experimental conditions quickly and reliably.
A Window into Barrier Health
TEER is more than just a measurement. It’s a window into the health and function of cell barriers. TEER provides researchers with a powerful tool to understand how our body's protective barriers work and fail. From studying neurological diseases affecting the blood-brain barrier to investigating inflammatory bowel conditions that compromise intestinal integrity, TEER measurements offer valuable insights into human health and disease. Whether studying disease, testing new therapies, or engineering advanced models, TEER provides a reliable, quantitative tool to advance discovery.
For researchers embarking on barrier function studies, mastering TEER measurement techniques opens doors to a wealth of research possibilities. Whether investigating fundamental cell biology questions or developing the next generation of therapeutic interventions, TEER remains an indispensable tool in the modern researcher's toolkit.
Understanding and properly implementing TEER measurements can significantly enhance research quality and contribute to advancing our knowledge of how biological barriers protect and maintain human health. As we continue to face new health challenges, from neurodegenerative diseases to inflammatory conditions, TEER measurements will undoubtedly play a crucial role in developing effective solutions.
At WPI, we proudly support scientists worldwide with trusted TEER instruments and accessories that make barrier research accessible, accurate, and reproducible.
