Visualization of diffusion pathways across the stratum corneum of native and in-vitro-reconstructed epidermis by confocal laser scanning microscopy

Abstract

Confocal laser scanning microscopy is a technique that permits the direct visualization in unfixed material of diffusion pathways and the cellular distribution of fluorescent markers after topical applications. This approach, in which the tissue specimen is optically sectioned, allows the study of changes in distribution pattern of applied compounds depending on the vehicle, time and depth without the interference of chemical alterations induced by most of the current techniques used for such studies. Using this technique the permeability properties of in-vitro-reconstructed epidermis were compared with those of the native counterpart. The epidermis was reconstructed by culturing human adult keratinocytes at the air-liquid interface either on fibroblast-populated collagen or on de-epidermized dermis. A fluorescent probe--Nile red (NR)--was applied in three different vehicles--polyethylene glycol (PEG) with a molecule mass of 400 (Da), propylene glycol (PG) and dimethyl sulphoxide (DMSO)--which perturb the SC barrier function to different extents. When NR was applied in PEG and PG on native epidermis, the amount of NR penetrating into and through the SC was very low, but was markedly increased when NR was applied in DMSO. Unlike native epidermis, the reconstructed epidermis allowed rapid NR penetration after the application in any of the solvents used. Furthermore, NR applied on reconstructed epidermis, was distributed quite homogeneously between the cellular and the intercellular spaces throughout the SC, suggesting that not only intercellular lipid structures but also the properties of the cornified envelopes differed markedly from those found in native epidermis.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo confirmation of hydration-induced changes in human-skin thickness, roughness and interaction with the environment

“…[50][51][52] This observation is consistent with a statement by Loth that the transport of water within the SC disjunctum takes place through spreading into the intercellular space due to the capillary forces, whereas the much slower and less straightforward water transport within the SC conjunctum is based only upon diffusion. 18,[53][54][55] This also explains the observation that the closer to the surface of the skin, the faster and more significant is the water uptake as well as the fact that even a short exposure to water (2 min) caused appreciable changes in the SSC.…”

Particle size of liposomes influences dermal delivery of substances into skin

“…Turner and Guy showed in 1998 that iontophoresis significantly enhanced the delivery of calcein into hairless mouse skin, particularly via follicular structures (Turner and Guy, 1998). Simonetti et al (1995) visualized diffusion pathways across the SC of native and in vitro reconstructed epidermis by using CLSM. Fig.…”

To freeze or not to freeze: adaptations for overwintering by hatchlings of the North American painted turtle

“…The resistance of the shell to penetration by growing crystals of ice has not been studied, but we predict that β-epidermis is an effective barrier to inoculation right from the time of hatching. This prediction is based on studies indicating (1) that scutes covering the shell are largely impermeable to water (Rose, 1969), (2) that water traverses the epidermis of mammalian integument via intercellular spaces (Elias and Friend, 1975;Nemanic and Elias, 1980;Simonetti et al, 1995;Meuwissen et al, 1998) and (3) that intercellular spaces are absent from the β-keratin layer overlying the shell of turtles (Alibardi and Thompson, 1999;Alibardi, 2002). Assuming that crystals of ice grow through the same channels that are followed by water, we hypothesize that ice is unable to penetrate integument overlying the shell of hatchling painted turtles owing to the absence of pathways through which the crystals might grow.…”