Chronological aging impacts abundance, function and microRNA content of extracellular vesicles produced by human epidermal keratinocytes.

The disturbance of intercellular communication is one of the hallmarks of aging. The goal of this study is to clarify the impact of chronological aging on extracellular vesicles (EVs), a key mode of communication in mammalian tissues. We focused on epidermal keratinocytes, the main cells of the outer protective layer of the skin which is strongly impaired in the skin of elderly.

Elastogenic potential and antisagging properties of a novel Murraya koenigii extract.

Background: The process by which functional elastic fibers are produced, namely elastogenesis, is complex and difficult to assess in vitro. Identifying efficient elasticity-boosting ingredients thus represents a challenge.

Aims: The elasticity-boosting properties of a novel extract of Murraya koenigii leafy stems were assessed in vitro in 3D culture models before being evaluated in human female volunteers.

Maintenance of Chronological Aging Features in Culture of Normal Human Dermal Fibroblasts from Old Donors.

Chronological aging is defined as a time-dependent decline of tissue homeostasis which severely impacts skin. Understanding the mechanisms of skin aging is an active research area limited by the lack of relevant in vitro models. Being a component of aging, replicative or stress-induced senescence is repeatedly used to mimic skin aging in vitro, thus presenting only a partial view of the complexity of aging.

Tspan8 Drives Melanoma Dermal Invasion by Promoting ProMMP-9 Activation and Basement Membrane Proteolysis in a Keratinocyte-Dependent Manner.

Melanoma is the most aggressive skin cancer with an extremely challenging therapy. The dermal-epidermal junction (DEJ) degradation and subsequent dermal invasion are the earliest steps of melanoma dissemination, but the mechanisms remain elusive. We previously identified Tspan8 as a key actor in melanoma invasiveness.

Keratinocyte stem cells are more resistant to UVA radiation than their direct progeny.

The epidermis undergoes constant renewal during its lifetime. This is possible due to a special population of keratinocyte stem cells (KSCs) located at the basal layer. These cells are surrounded by their direct progeny, keratinocyte progenitors or transient amplifying cells (TAs), which arise from cell division.

Mitochondrial damage and cytoskeleton reorganization in human dermal fibroblasts exposed to artificial visible light similar to screen-emitted light.

Background: Artificial visible light is everywhere in modern life. Social communication confronts us with screens of all kinds, and their use is on the rise. We are therefore increasingly exposed to artificial visible light, the effects of which on skin are poorly known.

Long-term Genoprotection Effect of Sechium edule Fruit Extract Against UVA Irradiation in Keratinocytes.

Photoprotection is essential to prevent the long-term deleterious effects of ultraviolet (UV), including skin cancer and photoaging. So far, there has been an increase in the use of natural bioactive phytochemicals for the development of more effective skin photoprotective agents. However, the molecular mechanisms underlying the photochemoprotection activity of such compounds remain largely unknown.

α6 Integrin (α6)/Transferrin Receptor (CD71) Keratinocyte Stem Cells Are More Potent for Generating Reconstructed Skin Epidermis Than Rapid Adherent Cells.

The epidermis basal layer is composed of two keratinocyte populations: Keratinocyte Stem cells (KSC) and Transitory Amplifying (TA) cells that arise from KSC division. Unfortunately, no specific marker exists to differ between KSC and TA cells. Here, we aimed at comparing two different methods that pretended to isolate these two populations: (i) the rapid adhesion method on coated substrate and (ii) the flow cytometry method, which is based on the difference in cell surface expressions of the α6 integrin and transferrin receptor (CD71).

In vitro glycation of an endothelialized and innervated tissue-engineered skin to screen anti-AGE molecules.

Glycation is one of the major processes responsible for skin aging through induction of the detrimental formation of advanced glycation end-products (AGEs). We developed an innovative tissue-engineered skin combining both a capillary-like and a nerve networks and designed a protocol to induce continuous AGEs formation by a treatment with glyoxal. We determined the optimal concentration of glyoxal to induce AGEs formation identified by carboxymethyl-lysin expression while keeping their toxic effects low.

A new organotypic model containing dermal-type macrophages.

Human skin equivalents (SEs) are popular three-dimensional (D) cell culture systems in fundamental and applied dermatology. They have been made to contain dendritic cells, but so far no study on the incorporation of potentially anti-inflammatory dermal macrophages has been performed. Here, we show that monocyte-derived dermal-type macrophages can be introduced into a rigid scaffold with dermal fibroblasts.

Modulation of CD86 expression in skin dendritic cells does not always correlate with changes in DC motility, migration and allostimulatory functions.

CD86 expression is a well-known activation marker of dendritic cells (DC). In this study, we compared the level of CD86 expression in monocyte-derived skin DC with their motility, migratory abilities and allostimulatory capabilities. We show that motility and migration could be uncoupled from activation and that the immune response-modulating effects of certain compounds may correlate with down-regulation of CD86 expression rather than with effects on motility and migration.

Evolution of three dimensional skin equivalent models reconstructed in vitro by tissue engineering.

Since the culture of keratinocytes on feeder layers, research to produce skin equivalents has been motivated by the challenge of treating large burns and chronic wounds and by European regulations which both require proof of the innocuousness and the effectiveness of cosmetic products, and which forbid animal testing. The dynamism in fundamental research, dermocosmetology and the pharmaceutical industry has led to the evolution and complexification of reconstructed skin. The Collagen-GAG-Chitosan sponge, as well as the self-assembly model, allow dermal reconstruction in which the neosynthesized extracellular matrix contains all of the desired macromolecules.

Variations in the characteristics of keratocytes in culture in relation to their location in human cornea.

To reconstruct artificial stroma close to corneal stroma, it is necessary to use keratocytes with high proliferative potential that maintain the keratocyte phenotype as characterised by CD34. To select such cells, we tested the proliferative potential and characterised the keratocytes isolated from 4 different areas of the human cornea: superior perilimbal, inferior perilimbal, superior central and inferior central. Keratocytes isolated from these different areas had significantly different growth rates (p<0.

Effects of solar ultraviolet radiation on engineered human skin equivalent containing both Langerhans cells and dermal dendritic cells.

Exposure of human skin to solar ultraviolet (UV) light induces local and systemic immune suppression. It is known that alterations of immune functions of Langerhans cells (LCs) and dermal dendritic cells (DDCs) mediate this phenomenon. The purpose of this study was to mimic in vitro the early UV-induced skin disruption to better understand the involvement of the skin micro-environment in triggering this immunosuppressive state.

Development of a hemicornea from human primary cell cultures for pharmacotoxicology testing.

We report the reconstruction and characterization of a hemicornea (epithelialized stroma), using primary human cells, for use in research and as an alternative to the use of animals in pharmacotoxicology testing. To create a stromal equivalent, keratocytes from human corneas were cultured in collagen-glycosaminoglycan-chitosan foams. Limbal stem cell-derived epithelial cells were seeded on top of these, giving rise to hemi-corneas.

Development of an optimised culture medium for keratocytes in monolayer.

Unlabelled: Our objective was to formulate a medium for monolayer culture optimising both keratocyte growth and preservation of the keratocyte phenotype.

Methods: An experimental matrix selected 14 media to test, using 7 components. Selection criteria were growth rates over 5 passages and expression of the CD34 marker.

Evolutive skin reconstructions: from the dermal collagen-glycosaminoglycan-chitosane substrate to an immunocompetent reconstructed skin.

The development of human skin models that have the same properties as genuine human skin is of particular significance. Very promising skin models are the three-dimensional artificial skin constructs, which, similar to genuine skin, consist of an epidermis of differentiated keratinocytes and a dermis. A skin equivalent based on a collagen-glycosaminoglycan-chitosan dermal substrate has been developed to meet the growing demand in tissue engineered skin equivalents.

Mixed Langerhans cell and interstitial/dermal dendritic cell subsets emanating from monocytes in Th2-mediated inflammatory conditions respond differently to proinflammatory stimuli.

The skin harbors two dendritic cell (DC) subsets, Langerhans cells (LC) and interstitial/dermal DC (IDDC), which traffic to lymph nodes after inflammation and ultraviolet stress. To demonstrate that monocytes may act as DC precursors for skin DC in postinflammatory recolonization, we generated LC and IDDC from monocytes by using cytokines related to the T helper cell type 2 environment [granulocyte macrophage-colony stimulating factor/transforming growth factor-beta/interleukin-13/tumor necrosis factor alpha (GM-CSF/TGF-beta/IL-13/TNF-alpha)]. In this study, skin DC [LC as Langerin/CD207(+) cells and IDDC as DC-specific intercellular adhesion molecule-grabbing nonintegrin (SIGN)/CD209(+) cells] displayed desynchronized programs along their differentiation, activation/maturation processes in response to stimuli characteristics of a proinflammatory context.

When integrated in a subepithelial mucosal layer equivalent, dendritic cells keep their immature stage and their ability to replicate type R5 HIV type 1 strains in the absence of T cell subsets.

Many potential targets of human immunodeficiency virus type 1 (HIV-1) reside in the human reproductive tract, including dendritic cells (DC). The ability of these cells to replicate HIV-1 is dependent on many factors such as their differentiation/maturation stage. Nevertheless, precise mechanisms underlying the early steps of transmucosal infection are still unknown.

In vitro reconstructed mucosa-integrating Langerhans' cells.

All three-dimensional in vitro mucosal models constructed, thus far, have only been reconstituted by epithelial cells. We have developed a reconstructed oral and vaginal epithelium that integrates Langerhans' cells (LC), the dendritic cells (DC) of malpighian epithelia. The epithelium was composed of gingival or vaginal keratinocytes seeded on a de-epidermized dermis (DED) and grown in submerged culture for 2 weeks.

Antagonistic effects of IL-4 and TGF-beta1 on Langerhans cell-related antigen expression by human monocytes.

In this study, we analyzed the specific effects of transforming growth factor beta (TGF-beta1) and/or IL-4 on monocyte-derived cells. Monocytes were cultured with GM-CSF, GM-CSF/TGF-beta1, GM-CSF/IL-4, or GM-CSF/IL-4/TGF-beta1 before cell morphology, phenotype, and function were assessed. As expected, interleukin-4 is mandatory for monocyte differentiation into potent allostimulatory DC.

Penetration of human metastatic melanoma cells through an authentic dermal-epidermal junction is associated with dissolution of native collagen types IV and VII.

The events occurring during the penetration of melanoma cells through the dermal-epidermal junction, which is the first crucial step in the process of metastasis, are poorly understood, partly because no suitable tissue models exist. In the in vitro model reported here, two melanoma clones (T1C3, which generates lung metastases in experimental animals, and IC8, which does not) derived from a single parental cell line were co-seeded with normal allogenic keratinocytes onto acellular human de-epidermized dermis with preserved intact basement membrane and cultured for up to 1 month at an air-liquid interface. Histological, immunohistochemical and ultrastructural studies showed that melanoma cells from the metastatic clone (T1C3), but not from the non-metastatic clone (IC8), penetrated the dermal-epidermal junction to invade the dermis after 3 weeks of culture.