How Skin Wounds are Healed
Healing of a skin wound in mammals is a mixture of regeneration (creation of the same cell types as originally damaged) and replacement (substitution of a new cell type for an old one). Scarring is the result of replacement, so the more regeneration that can occur, the less scarring will be left behind after wound healing.
Wound healing follows a predictable course and time line in mammals. Presence of pathogens and patient health issues can lengthen the recovery time (Hackam and Ford, 2003).
Within a few minutes of the initial damage to the tissue, which almost always results in trauma to blood vessels, a plug of platelets and other blood products (blood clot) forms at the site of tissue damage and stops further loss of blood.
Within hours, debris-eating white blood cells called neutrophils have invaded the area of damage, signaling the start of the inflammation response. Inflammation is a series of events that includes increased blood flow, increased blood vessel permeability, activation of pain receptors and intense consumption of cell debris and bacteria by neutrophils and other white blood cells. Neutrophils ingest introduced bacteria and dead and dying cells in the wound, and are themselves killed in the process. The accumulating mixture of dead neutrophils and fluid forms pus. Typically within a few days, the surface of the clot has dried to form a scab. Now macrophages (another type of specialized white blood cell) infiltrate the wound, where they ingest dead neutrophils and other cellular debris.
Inflamation stage in deep wound cases appears to be a critical step to completion of the healing process. Inhibiting the early inflamation appears to slow recovery. Application of any anti-inflamitory, including emu oil, is discouraged during the first 24 hours. Anticdotal reports suggest timing emu oil applications to begin with the start of the proliferation phase (approx. 24 hours)
Within a week
after the wound occurred, tough, fibrous cells called fibroblasts move in from surrounding connective tissue and start to multiply at the wound site. The fibroblasts begin to secrete collagen fibers. At the same time, new epidermis begins to regenerate. New endothelial cells from neighboring undamaged tissue begin to form new capillaries that grow into the repairing wound site to supply blood to the newly forming epidermis.
Within a few weeks, the rapidly dividing epidermis completely lines the original wound site. The fibroblasts generate new connective tissue (scar tissues), which replaces the epidermis destroyed by the wound. Scar tissue persists after the healing of particularly severe wounds. Anticdotal reports link emu oil use to reduced scar tissue. If this is due to an increase in the ratio of epidermal cells to new scar tissues, continuing the application of emu oil through the entire healing cycle (about 3 weeks) might be beneficial.
The rapidity and effectiveness of skin wound repair depends on several factors (Burns et al., 2003). Proper nutrition is essential (Russell 2001). Vitamins C, D, E, and K all play important roles at some stage in the tissue repair process (Casey, 2003).
Agents that increase cell division, such as the emu oil, will also hasten wound healing (Snowden et al., 1997; Politis and Dmytrowich, 1998
; Lopez et al., 1999).