Characterization and ex vivo evaluation of excised skin samples as substitutes for human dermal barrier in pharmaceutical and dermatological studies

Abstract

Background Excised animal and human skins are frequently used in permeability testing in pharmaceutical research. Several factors exist that may have influence on the results. In the current study some of the skin parameters that may affect drug permeability were analysed for human, mouse, rat and pig skin. Materials and methods Classic biophysical skin parameters were measured (e.g. pH, hydration, permittivity, transepidermal water loss). Physiological characteristics of the skins were also analysed by confocal Raman spectroscopy, scanning electron microscopy and two‐photon microscopy. Results Based on biophysical testing, skin barrier function was damaged in psoriatic mouse skin and in marketed pig skin. Hydration and pH values were similar among the species, but freezing and thawing reduced the water content of the skins and shifted the surface pH to acidic. Aging reduced hydration and permittivity, resulting in impaired barrier function. Mechanical sensitization used in permeability studies resulted in proportional thinning of dead epidermis. Discussion Results indicate that depending on the scientific question it should be considered whether fresh or frozen tissue is used, and for certain purposes rodent skins are well usable. The structure of the skin tissue (ceramide, cholesterol, keratin, natural moisturizing factor or urea) is similar in rats and mice, but due to the higher skin thickness the lipid distribution is different in porcine skin. Psoriasis led to irregular chemical composition of the skin. Conclusion A comprehensive evaluation of skin samples of four species was performed. The biophysical and microscopic observations should be considered when selecting drug penetration models and experimental conditions.

Molecular distribution in intradermal injection for transfer and delivery of therapeutics

“…Hair removal cream (Nair hair removal lotion, Nair) was applied to the skin for 3-5 min and cleaned thoroughly with 70% ethanol. All experiments were performed within an hour of animal sacrifice to ensure both the integrity and viability of the skin (Oesch et al, 2014;Kocsis et al, 2022).…”

4′-OH as the Action Site of Lipids and MRP1 for Enhanced Transdermal Delivery of Flavonoids

“…By contrast, the coincubation of LiQ or Lic A with Cer did not cause these changes (Figure ). Compared with the porcine skin, the rat skin contained significantly lower lipid content, therefore providing a lower amount of interaction sites for flavonoid binding and diffusional barrier for drug transport. ,, Thus, the R values of Gla 1 and Lic B were significantly reduced, and the Q 1 of the LiQT, IsLT, Gla 1, Lic A, and Lic B on the rat skin was significantly enhanced (Figure S5). Collectively, 4′-OH served as the action site to specifically grab the CO group of the lipid and then disturb the lipid arrangement for enhanced transdermal delivery of flavonoids.…”

In vivo transepidermal water loss: Validation of a new multi‐sensor open chamber water evaporation system Tewameter TM Hex

“…Instrumentation technology for transepidermal water loss (TEWL) assessment has not been substantially modified since its introduction by Nilsson in 1977 when a method for direct measurement of the rate of evaporation from the skin surface has been described 1–4 . Classically two sensor pairs for relative humidity (rH) and temperature are placed in an open chamber to detect the concentration difference along increasing distance from the skin.…”