5.5B: Epidermal Wound Healing
Epidermal wound healing describes the mechanism by which the skin repairs itself after injury.
- Characterize epidermal wound healing
Key Points
- Epidermal wounds are typically less severe than those affecting the dermis.
- Clotting may not occur if there is no breaching of the vasculature; however, an immune response is still generated as the wound site is susceptible to infection.
- Proliferation is not required as the dermis remains intact and is able to independently re-constitute the basement membrane required for re-epithelialization.
- Keratinocytes surrounding the wound site, and epidermal cells found in dermal appendages (such as hair follicles ), are able to re-epithelialize the wound site.
- Little remodeling will occur as the original, mature extracellular matrix remains intact.
- Epidermal wounds often resolve quickly and have fewer potential issues than deeper wounds.
Epidermal wound healing refers to the repair of the epidermis in response to wounding. Epidermal only wounds are typically less severe than those affecting the dermis and so stages of the wound healing response may be missed.
As the epidermis is itself not vascularised—it is receiving blood from the dermis—a clotting and vasoconstrictive response is often not necessary. Immune cells may still be recruited to the wound site because the removal of the epidermal barrier makes the wound susceptible to infection.
Since the dermis is intact, local fibroblasts are able to contribute to the formation of a new basement membrane, upon which the epidermis sits. In very minor wounds even the basement membrane might remain intact, allowing for rapid re-epithelialization.
Keratinocytes—epidermal epithelial cells—around the wound site migrate across the wound and close it. Additionally, epidermal cells from dermal appendages, such as hair follicles, can contribute to wound closure.
Since the dermis and underlying tissue have not been damaged very little remodelling is required. As such, small wounds only in the epidermis typically heal rapidly and are often not observable (e.g., via the formation of scar tissue) within a period of months.