Skin Barrier Function and Hydration

Q: What is the difference between an ex vivo and an in vitro model?

Both in vitro and ex vivo models exhibit distinct test-specific characteristics. An ex vivo model typically includes an organ or tissue taken from a living body that has similarities in form to the human body and is capable of mimicking the physiological environment. Its benefit is that it will better capture the original shape and function of the tissue, and is appropriate for studying intricate biological phenomena. The in vitro model is a model that is based on cell culture and other technologies, which is convenient to work on, short time of experiment, and does not disturb complex factors in the body, thus makes it easy to study single or compound factors.

The skin is the largest organ of the body, and it performs many of the functions essential to human health. Not only does it protect the body from microbes and harmful chemicals, but also prevents the body from losing water. A healthy skin barrier keeps the skin soft, supple and smooth, and it also recovers quickly after physical and chemical stimuli. But a weakened skin barrier results in dryness, flaking, bruising and itching. More serious situations may also cause a number of skin diseases like eczema, acne, keratosis pilaris, and psoriasis.

Thus, not only is the skin barrier physically protecting the body from damage, but also shields it against pathogens and UV rays and chemicals by generating antimicrobial peptides and maintaining proper pH and hydration. Hydration of the skin is associated with barrier function, which consists of the following:

Cellular structure: Keratinocytes, Squamous cells, etc. Through tight junctions and the stratum corneum, these cells maintain physical security.
Natural moisturizing factors (NMF): Includes amino acids, urea and lactic acid to help skin maintain moisture levels in low humidity conditions.
Lipids: The lipid bilayer of stratum corneum has ceramides, cholesterol and fatty acids which keep the water from evaporating.
Glycerol: A natural endogenous moisturizer.
Proteins: Like keratin and natural humectants keep the skin moist and soft by retaining water.
Hyaluronic acid (HA): Hydrates and strengthens the dermis.

Fig. 1. Schematic structure of the skin barrier and "brick and mortar" model (Yang G, Seok J K, et al., 2020).

The right skincare routine contributes to the maintenance and repair of skin barrier integrity. And the efficacy of a product depends on the formulation and ingredients. Creative Bioarray provides evaluation assays using in vitro 3D skin tissue models that provide insights into skin barrier changes to facilitate the screening of more effective cosmetic formulations and the development of more effective skincare strategies.

Our Services

Assay	Content
Transdermal water loss (TEWL) assay	By mounting the skin on a diffusion cell, allowing the underside of the skin to contact the receptor medium in the receiving chamber. The moisture near the outer surface of the skin is measured to evaluate the rate at which water passes from the underside through the skin barrier.
Electrical impedance assay	Measure the electrical current passing through the skin, assessing changes in skin resistance to evaluate both the integrity of the skin barrier and variations in moisture content.
Stimulation epidermal differentiation assay	E.g. filaggrin, involucrin, transglutaminase, cytokeratins
Lipid synthesis (acid mantle) assay	Sebaceous lipids Epidermal lipids (e.g. ceramides, cerebrosides and phospholipids)
Epidermal Extracellular Matrix Component Expression or Synthesis Assay	Glycosaminoglycans and hyaluronic acid Proteoglycans and ECM receptors Proteases (e.g. MMPs)
Epidermal Adhesion and Intercellular Junction Marker Expression Assay	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)

Available in vitro or ex vivo models:

From our service, you can:

Obtain the effective ingredients of a product or the composition of an effective formula.
Explore in depth the mechanism of different ingredients in skin barrier and moisturization.
Understand the moisturizing effect of a product under different environmental conditions and anticipate its performance in daily life.
Get targeted suggestions for product optimization.

Service Features

Scientific rigor: Advanced testing technology and comprehensive assessment methods are used to ensure the accuracy and reliability of the results.
Comprehensive assessment: From skin barrier function to moisture management effect, the key indicators of product performance are fully covered, providing a comprehensive basis for product optimization.
Efficient guidance: Rapid identification of compounds and active ingredients in formulations shortens the product development cycle.
Innovative technology: Adopting advanced in vitro 3D modeling and ex vivo models, test results are effectively interpolated to the human body.

FAQ

Q1: What is electrical impedance testing for skin barrier and hydration testing?

Electric resistance is closely related to the moisture in the skin. The more water in the skin, the greater the electrical conductivity and the lower the resistance value; the less water in the skin, the greater the electrical conductivity and the higher the resistance value. Therefore, electrical impedance testing indirectly detects skin water content.

Q2: What is TEWL testing?

TEWL stands for Transepidermal Water Loss, which indicates the amount of water that has left the skin via the epidermis. TEWL is a marker of skin barrier function, the ability to hold in water. If the barrier to the skin is broken, TEWL levels will increase, indicating the loss of water in the skin. By measuring the skin's TEWL value while it was in and without a product or treatment, it's easy to visually observe how the barrier function of the skin has altered or deteriorated.

Q3: What is the difference between an ex vivo and an in vitro model?

Both in vitro and ex vivo models exhibit distinct test-specific characteristics. An ex vivo model typically includes an organ or tissue taken from a living body that has similarities in form to the human body and is capable of mimicking the physiological environment. Its benefit is that it will better capture the original shape and function of the tissue, and is appropriate for studying intricate biological phenomena. The in vitro model is a model that is based on cell culture and other technologies, which is convenient to work on, short time of experiment, and does not disturb complex factors in the body, thus makes it easy to study single or compound factors.

Quotation and Ordering

If you have other questions, please contact us and we will provide you with detailed explanations. Our customer service representatives are available 24hr a day! Thanks for choosing Creative Bioarray services!

Reference

Yang G, Seok JK, et al. Skin Barrier Abnormalities and Immune Dysfunction in Atopic Dermatitis. Int J Mol Sci. 2020. 21(8):2867.

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