The importance of skin barriers in managing periwound areas


The importance of the skin barrier in managing periwound areas


The skin is the largest of the body’s organs and provides an immediate barrier between the internal tissues and the environment. It protects the body from the effects of temperature and chemical and microbial attack. At the same time as preventing harmful substances from entering the body, the skin also prevents the loss of nutrients. This article explains how the skin’s structure helps to protect the body.


INTRODUCTION This short report describes the six aspects of skin biology that combine to create the skin barrier, which protects the internal tissues from potentially harmful environmental effects.


These are: n


n n n


Epithelial regeneration Epidermal differentiation Formation of tight junctions Lipids


n Microbial flora n Antimicrobial peptides


This article also provides key tips for practice in relation to managing periwound skin.


EPITHELIAL REGENERATION All epithelia are constantly regenerating. This constant turnover of cells results in a loss of superficial cells together with any microbes present on the skin’s surface. Thus, as well as preventing microbes from gaining a foothold, continued epidermal regeneration also means that minor breaches in the skin’s barrier function are automatically repaired [Fig 1]. The process of epidermal regeneration is


interesting because only the adult tissue stem cell, known as the keratinocyte stem cell, is a permanent resident cell — the remaining keratinocytes (the name given to cells in the skin’s epidermis) are eventually shed. The keratinocyte stem cell resides at the bottom of the epidermis on top of a thin layer of basement membrane and is depicted in Fig 1 as the cell with the yellow nucleus. The keratinocyte stem cell divides


infrequently, but when it does so it splits to form another keratinocyte stem cell (in a process called self-renewal) and a transient amplifying cell (depicted in Fig 1 with a green


nucleus — this division is demonstrated by the yellow arrows). In turn, these transient amplifying cells subsequently divide to populate the basal cell layer (demonstrated by the green arrows in Fig 1), but they do so for a finite period of time; after which they are no longer able to divide. Eventually, the transient amplifying cells and their progeny rise into the suprabasal layers as new transient amplifying cells occupy the basal cell layer beneath them — in so doing they progress up the epidermis until they are also eventually shed from the surface. Thus, during normal epidermal homeostasis, only the keratinocyte stem cell survives intact and all other cells are eventually shed over a period of approximately 28 days.


EPIDERMAL DIFFERENTIATION In common with all epithelia tissues that are responsible for lining the body against the environment, the skin’s epidermis relies upon a highly regulated process called terminal differentiation to form an impenetrable outer layer. Proliferation at the basal layer, including among the slow-dividing keratinocyte stem cells, gives rise to some suprabasal cells that


Author: Girish Patel


Useful links and further reading


Compression in Venous Leg Ulcers: a consensus document


Innovations in the care of the skin surrounding pressure ulcers


Page points


1. All epithelia are constantly regenerating, resulting in a loss of superficial cells together with any microbes present on the skin’s surface


2. Continued epidermal regeneration also means that minor breaches in the skin’s barrier function are automatically repaired


3. The epidermis relies upon a highly regulated process called terminal differentiation to form an impenetrable outer layer


Figure 1 – Epidermal regeneration.


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