Characterization of a New Reconstructed Full Thickness Skin Model, T-Skin™, and its Application for Investigations of Anti-Aging Compounds.

Background: We have characterized a new reconstructed full-thickness skin model, T-Skin™, compared to normal human skin (NHS) and evaluated its use in testing anti-aging compounds.

Methods: The structure and layer-specific markers were compared with NHS using histological and immunohistological staining. In anti-aging experiments, T-Skin was exposed to retinol (10 µM) or vitamin C (200 µM) for 5 days, followed by immunohistological staining evaluation.

Effect of vitamin C and its derivatives on collagen synthesis and cross-linking by normal human fibroblasts.

Vitamin C (VitC) plays a critical role in the maintenance of a normal mature collagen network in humans (anti-scurvy properties) by preventing the auto-inactivation of lysyl and prolyl hyroxylase, two key enzymes in collagen biosynthesis. In this study two in vitro models were designed to evaluate the effects of VitC on collagen biosynthesis and cross-linking at cellular and tissue levels. It was shown that VitC induced a dose-dependent increase in collagen type I deposits by normal human fibroblasts (NHF) cultured in monolayer, and enhanced extracellular matrix contraction by NHF in a lattice model, in a non-cytotoxic range of concentrations (103m, 104m, 105m).

Biphasic effects of minoxidil on the proliferation and differentiation of normal human keratinocytes.

Minoxidil is the most used drug with proved effects in the treatment of androgenetic alopecia (AGA), but little is known about its pharmacological activity and target cells in hair follicles. As AGA is characterized by follicle atrophy, accelerated hair cycles and hair fiber thinning, we postulated that keratinocyte proliferation/differentiation is affected and we tested Minoxidil's effects on those parameters. Normal human keratinocytes (NHK) of follicular or epidermal origin were cultured in the presence of Minoxidil (0, 0.

Messenger RNA expression of steroidogenesis enzyme subtypes in the human pilosebaceous unit.

In order to define the respective involvement of steroidogenesis enzymes subtypes in the control of hair follicle homeostasis, we evaluated, by semiquantitative RT/PCR, the expression levels of mRNAs coding for 17 beta-hydroxysteroid dehydrogenase type 1 and type 2, 3 beta-hydroxysteroid dehydrogenase, Cyt.P450-aromatase, steroid 5 alpha-reductase type 1 and type 2 and 11 beta-hydroxysteroid dehydrogenase. These assays were performed for several components of the pilosebaceous unit (PSU); fresh plucked anagen hairs, sebaceous glands and primary culture of dermal papilla, as well as other tissues involved in an active steroid metabolism (human testis, liver, placenta, prostate, ovary, uterus and adrenals) as controls.

A novel in vitro model for the study of human keratinocyte/leucocyte interactions under autologous conditions.

Keratinocyte/leucocyte interactions have become an area of intense investigations in the last decade. However, few convenient in vitro models are available at present. We have therefore designed a novel in vitro system for autologous human keratinocyte/leucocyte co-culture.

Repeated application of dinitrochlorobenzene to the ears of sensitized guinea pigs: a preliminary characterization of a potential new animal model for contact eczema in humans.

We have evaluated a subchronic model of contact hypersensitivity in the guinea pig to mimic human chronic/recurrent eczema. Repeated challenges of the ears of previously sensitized guinea pigs with 0.1% dinitrochlorobenzene (once a week for 4 weeks) induced a typical oedema response, which increased during the first 48 h after each challenge.