Cyanoacrylate Skin Surface/ Follicular Stripping

The stratum corneum (SC) is a dead structure. However, it exerts a unique barrier function partly protecting the living tissues from a series of environmental threats including ultraviolet light, microorganisms and irritant/toxic xenobiotics. In addition, the SC controls any excessive loss in water, electrolytes and macromolecules from the skin. In addition, the SC acts as a unique sophisticated biosensor that signals the underlying epidermis to respond to various external stimuli. Despite minimal metabolic activity, the SC corresponds to a highly specialised structure resulting from the continuous corneocyte renewal ideally keeping a steady state in the SC structure and thickness. However, corneocytes are structurally and biochemically heterogeneous. Over a vast part of the body, the SC is typically composed of 12–16 layers of fl attened corneocytes. These cells are about 1 μm thick and have a mean area reaching approximately 1,000 μm 2 . Of note, the corneocyte surface area is infl uenced by age, anatomical location and any conditions including chemical irritation and UV insults altering the epidermal renewal. In particular, the average corneocyte size apparently increases with age. This feature is assumed to be related to a prolonged transit time of corneocytes through the SC. Normal SC binds water and keeps its surface soft and smooth. Some of its molecular components bind water and/or prevent water evaporating from the skin surface. These compounds include the so-called natural moisturising factor (NMF), consisting of a mixture of water-soluble small molecules such as amino acids, lactate and urea, the intercellular lipids, sebum and specifi c protein components of corneocytes. Abnormalities in these components produce a harsh and hard SC that leads to the development of fi ne cracking and fi ssuring. In some instances, the SC homeostasis is altered. Indeed, the SC is the repository of many biologic events that previously infl uenced the underlying metabolically active keratinocytes. The SC structure is further altered by diverse and repeat external insults. The genetic background, the nutritional status, some physical agents, as well as drugs, cosmetics, toiletries and other chemical xenobiotics represent additional modulators of the SC structure. Knowledge about the fi ne SC structure is crucial in many respects in the fi eld of dermocosmetic science, particularly when dealing with age-related xerosis and effects of surfactants, emollients and squamolytic agents. G. E. Piérard , MD, PhD (*) C. PiérardFranchimont • P. Delvenne • P. Quatresooz Laboratory of Skin Bioengineering and Imaging, Department of Dermatopathology , University Hospital of Liège, CHU , Sart Tilman, Liège B-4000 , Belgium e-mail: [email protected] 22 Cyanoacrylate Skin Surface/ Follicular Stripping