Permeability of the reconstructed human epidermis model Episkin® in comparison to various human skin preparations

The objective of this work was to compare the barrier function of the small diameter reconstructed human epidermis model Episkin® (d = 12 mm) to human skin in vitro. For that purpose a modification for the Franz diffusion cell (d = 15 mm) had to be developed so as to allow direct comparison with the following human skin preparations: Full thickness skin (FTS), split thickness skin (STS), heat-separated epidermis (HSE), and trypsin isolated stratum corneum (TISC). Among the tested preparations, HSE appeared to be the most preferable due to its clear morphological structure and ease of preparation. The lipid profile of HSE and Episkin® was analyzed and showed significant differences in terms of cholesterol, ceramides and triglycerides contents, whereas cholesterol esters and fatty acids were not different. Permeation data with HSE and Episkin® were then gathered using caffeine and testosterone. Both test compounds permeated much faster through Episkin® than through HSE. Moreover, opposed to Episkin®, HSE differentiated between the two test compounds. In spite of the remarkable progress in developing RHEs in the past years at this time Episkin® can obviously not yet fully replace human skin for in vitro permeability experiments.