The strong societal urge to reduce the use of experimental animals have led to the development of primary keratinocyte-based alternative in vitro models for normal and diseased human skin. However, the availability and limited potential for genetic modification of primary keratinocytes hampers the large scale implementation of these models. Immortalized cell lines may overcome these issues, yet few immortalized human keratinocyte cell lines are available and most, e.g. the HaCaT cell line, do not reconstitute a fully stratified epidermis.
We compared two immortalized keratinocyte cell lines (N/TERT1, N/TERT2G) to human primary keratinocytes based on epidermal differentiation, response to inflammatory mediators, and the development of normal and inflammatory human epidermal equivalents (HEEs). We furthermore conducted a literature search on both cell lines to provide an overview of the use of N/TERT keratinocytes in the dermatological research community. 
We found that epidermal morphology, stratum corneum permeability, expression of epidermal differentiation genes and proteins, and host defence genes in N/TERT-HEE cultures was similar to that of primary human keratinocytes. We were able to generate HEEs with psoriasis or atopic dermatitis features from N/TERT keratinocytes and validated these models for drug-screening purposes. 
In conclusion, the herein investigated N/TERT keratinocyte cell lines are considered a useful substitute for primary human keratinocytes. We hereby provide a biologically relevant, unlimited cell source for in vitro studies on epidermal biology, inflammatory skin disease pathogenesis and therapeutics. Immortalized N/TERT keratinocytes may be a favourable keratinocyte cell line over the widely used HaCaT cell line. As N/TERT keratinocytes can be readily transfected and are amenable to genetic modification, they may be extremely useful in combination with gene editing technology, to study epidermal biology and disease.

Immortalized N/TERT keratinocytes: an excellent and versatile alternative for primary keratinocytes in experimental dermatological research