Conversations about the skin barrier are mainstream nowadays, and a vast range of products are available to repair, protect, soothe and calm our skin from supermarkets, pharmacies and beauty counters.

Assessing the integrity and vulnerabilities of our skin barrier

Our skin barrier can be disrupted for many reasons; some external factors like over-washing and exfoliating, poor air quality, stress, exhaustion, too much sun and exposure to irritants, and others inherent, such as genetics, ageing and pre-existing skin conditions. When it’s damaged, the tight arrangement between the skin cells is lost. This allows external irritants to penetrate more easily and leads to more water (moisture) leaving our skin. Common ‘active’ ingredients to combat these stressors include ceramides, hyaluronic acid, niacinamide, natural plant extracts and oils alongside more old school remedies such as glycerin and petrolatum. Damaged skin barrier is characterised by being easily irritated, dehydrated and having flaky or rough skin. Your skin is inflamed, irritated, tight, yet may be very oily. Understanding the skin barrier characteristics and sensitivities can help formulators target product development.

So how do we observe and quantify the effects of the lotions, potions and products that we use in our daily routines on our skin barrier. The answer is by measuring trans-epithelial electrical resistance (TEER) across the skin cells.

Evaluating and monitoring the skin barrier

Endothelial cells line the inside surfaces of the body, such as the inner layer of blood vessels, while epithelial cells line the outside surfaces, such as skin and most organs. Both cell types express tight junctions, allowing them to link tightly with neighbouring cells to form a selectively permeable ‘barrier’.

Thanks to trans-epithelial electrical resistance we can measure the integrity of this skin barrier. We can observe how it is affected when we apply a range of ingredients and products. And the results can be used to understand whether your substance is causing harm and compromising this natural line of defence, or to prove that it in fact helps skin barrier recovery. In other words, we can say that it gives us an understanding of the ‘mildness’ of ingredients and formulations.

TEER (trans-epithelial electrical resistance) is a well-established method of evaluating and monitoring epithelial tissue (skin, lungs, digestive tract, gums etc) in a non-destructive way. Barrier function can be stably monitored for minutes, hours, or days without disturbing the cells. The strength and integrity of these barriers is assessed via measurements of the electrical resistance across the cell layer. A low frequency current is applied, and the resistance of the barrier is measured. The easier the current flows between the cells the lower the TEER value, a reduced TEER value is an indicator of a compromised barrier.

TEER measurements are perfect add-on to skin and eye mildness testing from XCellR8 adding weight to your evidence of mildness. Speak to our sales team today about getting your lab slot reserved: or contact us now.