Topically applied, fatty acid-containing formulations provide superior barrier benefits in an ex vivo tape-stripped skin model

Objective

Ex vivo skin has been used to study various skin conditions from atopic dermatitis to burn injury. The aim of this research is to identify a more effective barrier improvement strategy and to evaluate topical formulations in replenishing the skin. The skin can create new longer chain fatty acids and ceramides (CERs) from topically applied skin natural fatty acid to help renew the skin's barrier.

Methods

An ex vivo skin model damaged by sequential tape stripping of the stratum corneum (SC) was used to investigate the repair of the SC. Confocal laser scanning microscopy was used to assess the SC layers recovered. Ultrastructural analysis was performed using transmission electron microscopy to visualize the lamellar bodies and intercellular lipid lamellae.

Results

The data in this study provide the first direct ex vivo evidence comparing different marketed formulations containing three CERs with those containing fatty acids. Free fatty acid (FFA)-containing formulations, but not CER-containing formulations, directly applied to the damaged skin, showed an increased number of repaired SC layers and this was reflected at the ultrastructural level by an increased intercellular lipid lamellae length and an increased number of lamellar bodies.

Conclusion

These findings demonstrate that FFA-containing formulations can repair damaged ex vivo skin and point to a repair mechanism in which topically applied palmitic and stearic acids, (which boost lipid levels and elongation) can increase the production and transport of lipids into a repaired SC and thus rebuild an effective skin barrier.