Scarring and the Skin Healing Mechanisms

The elimination or reduction of scars, lesions, and stretch marks from the skin depends on a process called "skin remodeling".

The skin is meant to heal wounds quickly to prevent blood loss and infections. Scars are crafted from a rapidly formed "collagen glue" that the body deposits into an injured area for protection and strength. In ideal skin repairing, damaged skin is rapidly closed, and then the healed area is slowly reconstructed to remove the residual collagen scars and blend the skin area into nearby skin.

Scar collagen is eliminated and replaced with a mix of skin cells and invisible collagen fibers. This remodeling may continue in a skin area for up to ten years.

In children, the remodeling rate is high and scars are often rapidly eliminated from injured skin areas. But as we become adults, this rate diminishes and small scars may stay there for years.

One way to quicken remodeling is to make a small amount of controlled skin damage with a needle, laser, acid, or other means, and then let the body repair processes reconstruct the skin area.

An alternative method is to use enzymes and fibroblast proliferators to increase the body's normal rebuilding mechanisms and achieve even better final results. Fibroblasts are the cells in the basal membrane of the skin and they are the precursors of all the structural elements of healthy skin, including those that provide moisture, tensile strength and elasticity to skin. Enzymes dissolve or "digest" damaged and dying cells.

Wound Repair Process

Scars are always needed to reconnect skin that has been injured. Initially, they may be red or dark and pink after the wound has healed but will become softer and flatter naturally over time, resulting in a flat, pale scar.

For reasons that are yet to be fully understood, some people suffer from raised scars that are red and thick and may cause itch or pain. Others develop scars that grow beyond the site of a wound, called keloid scars.

Keloid scars are actually thick, itchy, puckered scars that grow beyond the edges of a wound or incision and rarely regress. They appear when the body continues to produce tough, fibrous protein (known as collagen) after a wound has been repaired.

Keloid scars can appear after any type of injury to the skin, including scratches, tattoos, injections, insect bites or medical procedures. Keloid scars can appear anywhere on the body, but most commonly occur on earlobes, over the breastbone and on shoulders.

Keloids are fibrotic tumors characterized by a collection of atypical fibroblasts with excessive deposition of extracellular matrix components, especially collagen, fibronectin, elastin, and proteoglycans. Histologically, keloids contain relatively acellular centers and thick, abundant collagen bundles that form nodules in the deep dermal portion of the lesion. Keloids present a therapeutic problem that must be addressed as these lesions can cause significant pain, pruritus (itch) and physical disfigurement, may not improve in appearance over time, and can even limit mobility if located over a joint.

Hypertrophic scars use to be difficult to distinguish from keloid scars histologically and biochemically, but unlike keloids, hypertropic scars remain confined to the injury site and often mature and flatten out over time. Both types secrete larger amounts of collagen than normal scars, but typically the hypertrophic type shows declining collagen synthesis after about 24 weeks. Hypertrophic scars contain about twice as much glycosaminoglycans as normal scars, and this and enhanced synthetic and enzymatic reactions result in significant alterations in the matrix which affects the mechanical properties of the scars, including decreased extensibility that makes them feel firm.

As with hypertrophic scarring, people who have developed one keloid scar are likely to be prone to another one in the future and should alert their doctor or surgeon if they are going to need injections or to have any kind of surgery.

Atrophic scars are characterized by a thinning and diminished elasticity of the skin due to a loss of normal skin architecture. An example of an atrophic scar is striae distensae, also called stretch marks.