Scarring and the Skin Healing Mechanisms

The removal 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 avoid blood loss and infections. Scars are created from a rapidly formed "collagen glue" that the body deposits into an injured area for defense and strength. In ideal skin healing, damaged skin is rapidly closed, and then the healed area is slowly repaired 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 work 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 reach adulthood, this rate diminishes and small scars may stay there for years.

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

An alternative procedure is to use enzymes and fibroblast proliferators to increase the body's natural reconstructing 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 give 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 been healed but will become paler and flatter naturally over time, resulting in a flat, pale scar.

For reasons that are still waiting to be fully understood, some people form raised scars that are red and thick and may be itchy or painful. Others develop scars that extend beyond the site of a wound, called keloid scars.

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

Keloid scars can result from any type of injury to the skin, including scratches, insect bites, tattoos, injections or surgical procedures. Keloid scars can appear anywhere on the body, but most commonly occur over the breastbone, on earlobes 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 represent a therapeutic challenge 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 affect mobility if located over a joint.

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

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

Atrophic scars use to cause 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 known as stretch marks.