Dear Mahroo,

I'm assuming you'd want to count the cells in order to remove potential confounding of the TEER readings by confluence?

The short answer is that I'm not sure it's entirely necessary to count cells and normalise when measuring TEER.

I work with air-liquid interface cultures of primary airway epithelial cells, and I only start measuring TEER when they are fully confluent. I do not count the numbers of cells, but I do measure the resistance of a blank membrane with no cells to calculate the TEER value. Are your cultures fully confluent when you measure the TEER?

I have also read a paper (unfortunately I can't remember which one) where the frequency of the volt-ammeter used to measure TEER determines whether the reading is affected by confluency, or barrier function. Most commercial devices only measure at 12.5Hz, which is used to determine barrier function rather than confluency. If you want to build your own volt-ammeter with programmable frequency, I've found this excellent paper;

https://www.jove.com/t/60087/a-simple-approach-to-perform-teer-measurements-using-self-made-volt

Bear in mind that biophysics is not an area of expertise for me, so please correct me if I'm wrong.

If you're still keen to count you cells, you could look into using ImageJ to count from microscopy pictures, although this is not something I've tried myself.

Hope this helps!

Sam

Sam Siljee

Thank you Sam for your answer.

ya, I start measuring TEER one week after seeding, when they are fully confluent. I think it would be great if I could stain the nucleus and see the cells under the microscope after TEER measurement.