Skin hydration partly determines the aspect of the skin (dry, rough and oily skin, etc.). Through its barrier function, skin is our shield from external stress factors and prevents the evaporation of such essential elements as water, ions and amino acids.
Skin hydration is mostly linked to the skin barrier function. The role of a moisturizing skin care product is to act on skin surface to physically limit water loss (occlusive effect) or to act at the cellular level via different biological action models:
- reinforcement of the barrier function and of epidermal differentiation
- restoration of skin lipids
- stimulation of hygroscopic endogenous factors (water retention)
- improvement of cellular exchanges in solutes and in water
Hydration is a multifactorial process that cannot be understood through a single assay or model. It is therefore more conclusive to use a panel of complementary efficacy assays in order to study and demonstrate the hydrating properties of an active compound or cosmetic product.
HYDRATION AND REINFORCEMENT OF THE SKIN BARRIER FUNCTION: MODELS AND ASSAYS
Models
QIMA Life Sciences has many in vitro or ex vivo models at your disposal:
- normal human epidermal keratinocytes (NHEK)
- normal reconstructed human epidermis (RHE) & Reconstructed human epidermis in default
- sebocytes (SEBO662AR)
- full thickness skin (FTSK)
- skin explants (ex vivo)
Evaluation of skin barrier and hydration
We can evaluate case by case the hydrating effect of active compounds or formulations by measuring:
- the reinforcement of the barrier function
- the stimulation of the epidermal differentiation (e.g. filaggrin, involucrin, transglutaminase, cytokeratins)
- lipid synthesis (acid mantle):
- sebaceous lipids
- epidermal lipids (e.g. ceramides, cerebrosides and phospholipids)
- the expression or synthesis of epidermal extracellular matrix components:
- glycosaminoglycans and hyaluronic acid
- proteoglycans and ECM receptors
- proteases (e.g. MMPs)
- the expression of markers of epidermal cohesion and intercellular cell junctions:
- occluding junctions and attachment proteins (claudin, occludin, desmogleins, etc.)
- dermoepidermal junction (e.g. integrin V, collagen IV, collagen VII, etc.)
- gap junctions (e.g. connexins) and molecular channels (e.g. aquaporins)
Here are a few examples among all standard assays proposed by QIMA Life Sciences in the field of hydration and reinforcement of the barrier function:
HYDRATION AND REINFORCEMENT OF THE SKIN BARRIER FUNCTION: CLINICAL BIOANALYSIS
Analysis of lipids involved in the barrier function
Our company has developed ready-to-use non-invasive collection kits to analyze the lipids and biomarkers of the skin surface from your samples or from those of your clinical center.
The epidermal lipids involved in the barrier function of the epidermis (ceramides, fatty acids and cholesterol) are removed using the SW Kit.
The analysis of these lipids makes it possible to evaluate the quality of the intercorneocyte cement involved in the barrier function of the epidermis and in the prevention of transepidermal water loss (TEWL).
These evaluations help support your claims about the efficacy of biomimetic products, barrier products, protective products, moisturizers, etc.
Analysis of the components of the Natural Moisturizing Factor (NMF)
The amino acids and minerals present on the surface of the skin are collected using the SW Kit:
- PCA / UCA (cis/trans) – (catabolites of filaggrin)
- Amino acids
- Urea, lactates
- Mineral elements: Ca, K, Na, Mg, Zn, etc.
The analysis of these compounds makes it possible to evaluate the impact of the NMF component on skin hydration.
These analysis help support your claims about the efficacy of hygroscopic products, barrier products, protective products, moisturizers, etc.
Ceramide screening – LC/MS
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Damaged and healthy corneocytes – SEMX500
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PCA analysis – LC/UV
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