Stratum corneum keratin and intercellular lipid matrix (SC) (SC)

The stratum corneum (SC) represents the final stage of epidermal differentiation, functioning as the body's primary interface with the external environment. It is structurally characterized by the bricks and mortar model, where keratin-rich corneocytes (the bricks) are embedded within a continuous extracellular lipid matrix (the mortar) composed of ceramides, cholesterol, and free fatty acids (Elias, 2007; Menot et al., 2009). This complex serves a critical biological role in maintaining homeostasis by preventing excessive transepidermal water loss (TEWL) and acting as a physical barrier against pathogens, allergens, and chemical irritants (Proksch et al., 2008). In many dermatological diseases, such as atopic dermatitis and psoriasis, the SC is dysfunctional due to altered lipid composition or defective keratinization, leading to impaired barrier integrity and chronic inflammation (Bouwstra et al., 2003). Pharmacological targeting of the SC involves the use of keratolytics like salicylic acid to promote desquamation, humectants like urea to increase hydration, and physiological lipids to restore the intercellular matrix (Madison, 2003). Furthermore, the SC is the rate-limiting barrier for the percutaneous absorption of most topical drugs, making its modulation a key strategy in transdermal drug delivery systems (Prausnitz et al., 2008).

Other names

Skin barrierEpidermal barrierHorny layerCorneocyte-lipid matrix

Keratolysis, barrier restoration, occlusion, and humectancy