These results indicate that mechanical manipulation of the wound environment with a dynamic stress-shielding polymer device can significantly reduce scar formation.

SynopsisSunscreens provide broad-spectrum UV skin protection and contain more often UV filter combinations. Their efficacy reducing skin photo carcinogenesis and photo ageing is widely documented. However, there are many concerns about UV filter safety. Organic UV filters were the first targeted by scientist concerns, as they were showed to trigger skin allergic reactions. Inorganic UV filters were then at the heart of scientist debate especially because of their nanometric size. Over the last years, many studies have been published tending to highlight that organic as well as inorganic UV filters could lead to variable side effects after sunscreen application. However, these studies are still very controversial due to different experimental conditions and models. This review reveals that complementary studies using standardized methods are mandatory before ascertaining that UV filters threaten human health. R esum eLes produits solaires destin es a prot eger la peau contre les irradiations UV contiennent le plus souvent des combinaisons de filtres UV. Ces filtres permettent de r eduire le vieillissement pr ematur e de la peau ainsi que la survenue de cancer cutan e. Cependant, la nocivit e des filtres UV est toujours un sujet de controverse. Ainsi, des r eactions allergiques li ees a l'utilisation de produits solaires contenant des filtres UV organiques ont et e rapport ees dans la litt erature. R ecemment, l'utilisation de filtres UV min eraux a l' echelle nanom etrique, dispers es dans les produits destin es a la protection solaire a fait l'objet de travaux scientifiques visant a etablir le niveau de p en etration cutan ee. Ces derni eres ann ees, de nombreuses etudes ont et e publi ees tendant a montrer que les filtres UV organiques et inorganiques peuvent entrainer divers effets ind esirables. Mais, ces diverses etudes restent tr es controvers ees notamment a cause des diff erences dans les conditions exp erimentales et les mod eles utilis es. Cette revue r ev ele que des etudes compl ementaires utilisant des m ethodes standardis ees sont n ecessaires pour confirmer ou infirmer que les filtres UV pr esentent un risque sanitaire.

Several tight junction (TJ) proteins were detected in the living layers of adult human epidermis, and TJ-like membrane ridges were observed at the top of the stratum granulosum (SG) in freeze-fracture studies. We applied standard and immunoelectron microscopy to look for TJ-derived structures in the stratum corneum (SC) of human adult epidermis and in cornified envelopes purified from the plantar SC. Besides confirming claudin-1 labelling in the proximity of SG desmosomes, we also observed immunolocalization near corneodesmosomes in the lower SC. In addition, TJ proteins were consistently detected in the purified cornified envelopes. Lateral but not horizontal walls of the corneocytes showed frequent points of molecular fusion between lipid envelopes. These structural associations were very frequently localized at the top of the lateral corneocyte membranes, thus sealing the extremities of lateral intercorneocyte spaces. We propose that TJ-like structures persist in the SC and contribute to the reinforcement of lateral contacts and to the formation of membrane interdigitations between corneocytes. Their presence could contribute to subdivision of the extracellular spaces of SC into consecutive individualized compartments. Intercellular lipids, enzymes and other (glyco)protein content could thus evolve in the keratinized epidermal layer at different paces, as preprogrammed in the underlying living cells and influenced by the environment, e.g. humidity. Such situation might explain differences in the degradation rates between the 'peripheral' and the 'non-peripheral' corneodesmosomes observed during physiological desquamation, as previously suggested by us and others.Key words: cornified envelopes -desquamation -epidermal cohesionstratum corneum -tight junctions Accepted for publication 26 April 2011Human stratum corneum (SC) is the final product of epidermal differentiation that provides barrier function to the skin. Composed of cornified epithelial cells, called corneocytes, and sealed with the lipid-rich extracellular matrix, this thin epidermal layer is relatively impermeable to water and water-soluble substances. Like the entire epidermis, SC is constantly recycled in a highly regulated and interactive process in which superficial cell losses by desquamation at the skin surface are readily compensated by the conversion of the uppermost living keratinocytes into corneocytes (1,2). Such a programmed cell death is associated with several important changes in the cell shape and structure leading to the accumulation of flattened, laterally interdigitated, cornified keratinocytes forming the lower part of the SC, the SC compactum. During cornification, phospholipids of the keratinocyte plasma membrane are replaced by a single layer of ceramides. The latter are covalently bound by transglutaminase 1 to the protein envelope that is also cross-linked at the cell periphery by the same enzyme (3,4). The proper functioning of the SC barrier depends largely on its cohesion. Therefore, it is important to note tha...

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