Topically applied ceramide accumulates in skin glyphs

Area of Science:

• Dermatology
• Materials Science
• Biophysics

Background:

• Ceramides (CERs) are vital lipids in the stratum corneum (SC), essential for skin barrier function.
• Alterations in CER composition are associated with various skin conditions.
• The increasing use of CER-based skincare necessitates understanding their skin penetration.

Purpose of the Study:

• To investigate the spatial distribution and penetration profiles of topical ceramides (CERs) in ex vivo human skin.
• To compare the penetration of two different CER species and the influence of incubation time.

Main Methods:

• Topical application of single-chain perdeuterated sphingosine and phytosphingosine CER suspensions in oleic acid.
• Utilized Franz diffusion cells for ex vivo human skin application.
• Infrared imaging of microtomed skin sections after 24- or 48-hour incubation at 34°C.

Main Results:

• Both CER species accumulated in skin glyph regions and showed limited penetration into the SC within these areas.
• CER concentration profiles were heterogeneous and sparse, irrespective of CER species or incubation duration.
• Oleic acid exhibited more homogeneous distribution throughout the SC and epidermis compared to CERs.

Conclusions:

• Topical CERs exhibit a sparse and heterogeneous distribution within the stratum corneum, primarily localized in specific regions.
• The penetration profile of CERs is not significantly influenced by CER species or incubation time.
• Achieving a more uniform CER distribution in the SC may be crucial for optimal skin barrier enhancement.