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Keratinocyte growth factor, also known as KGF of FGF7, is important for wound healing. The growth factor cells are the first to begin moving over a wound, forming a new layer of skin. All movement and growth occurs underneath the wound scab. Keratinocyte growth factor is also a type of signaling cell, as it lets the body know that new cells are needed.
A growth factor is a compound that occurs naturally in the body and promotes cell growth. Typically, these compounds act as signaling molecules, attaching to cells and letting other compounds and enzymes in the body know where new cells are needed. They are also important for cell differentiation, or determining what type of cell the new ones will becomes.
Keratinocytes are a type of cell that is primarily found in the outermost layer of skin. Over 95% of all skin cells are kertinocytes. The main function of these cells is to provide protection from the environment and pathogens.
When the body is wounded, keratinocyte growth factor comes into play. Keratinocytes form a layer of epithelium that completely covers the wound in a process known as epithelialization. Epithelium is a one of the four main types of tissue. This tissue lines cells and surfaces of many structures found in the body, including skin.
This epithelialization is only one part of wound healing, normally occurring at the end of healing after inflammation. Existing epithelial cells will move across the wound to form new tissue. Typically, the keratinocyte growth factor cells are the first to move to the wound; mobilization begins only a few hours after the wound is inflicted.
In order to move, the keratinocyte growth factor cells must change shape, becoming flatter and longer. All movement occurs underneath the wound scab, eventually separating the scab from any underlying tissue. A moist environment promotes keratinocyte movement because moisture dissolves the scab, reducing its size and toughness.
A few days after the kerotinocyte growth factor begins to move, the cells will start to replicate, creating new skin cells. Cell formation is 17 times faster at the wound than anywhere else in the body. At first, only cells at the wound edges will replicate. When the entire wound is covered in new cells, then cell formation occurs on all cells covering the wound.
Once the keratinocyte growth factor meets in the middle of the wound, the cells stop moving. The growth factor begins to produce and release proteins that form the beginnings of cell membranes. New connections are made with existing skin cells until the break in the skin or epidermis is completely healed.