Skin Burn Treatments : Skin Deep, Cellular Wound Dressings

by Food and Drug Administration (FDA)

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Skin Deep

How a burn is treated and the type of cellular wound dressing used depends on the depth and extent of the burn and the overall health of the person burned.

Traditionally classified as first-, second-, or third-degree, burns are frequently classified by health professionals as superficial, partial thickness, or full thickness, depending on their depth and the amount of tissue damage. Superficial burns, such as a sunburn, redden the skin and damage only the epidermis, making it possible for the body to repair itself. Healthy cells from the dermis reproduce and migrate to the epidermis to heal the damaged skin.

Partial thickness burns cause blisters and damage all of the epidermis and part of the underlying dermis. Although these burns usually heal on their own when treated with cleaning and bandaging, if they are extensive or in a sensitive area, such as the face, they may benefit from the use of cellular wound dressings.

Full-thickness burns completely damage both the epidermis and the dermis, and may even destroy the underlying flesh and bones. The body is unable to heal itself properly because there are no healthy cells to regenerate. These burns require surgery to replace damaged skin with healthy skin, a process known as grafting. If these wounds are not treated, the body attempts to close them by forming scar tissue that contracts over time, leading to disfigurement and loss of motion in nearby joints.

In grafting of burn wounds, surgeons use healthy skin from another part of the person's own body (autografting) as a permanent treatment. But when the skin damage is so extensive that there is not enough healthy skin available to graft initially, surgeons may use cellular wound dressings. These temporary coverings help prevent infection and fluid loss until autografting can be performed. "And these products may allow surgeons to take thinner grafts because not as much dermis in the autograft is required," says Durfor.

An alternative to autografting is to use skin from another person (allograft) or from another species (xenograft) as a temporary covering to protect the wound.

Allografting uses skin from cadaver donors, and xenografting uses skin from animals. "Allografts provide the natural protection of human skin and are used most commonly. Xenografts of pigskin are sometimes used if allografts are not available," says Steven Boyce, Ph.D., director of the department of tissue engineering at Shriners Burns Hospital in Cincinnati. "Xenografts of pigskin are in plentiful supply and it's the closest anatomically to human skin."

Allografts and xenografts are temporary measures because, within several weeks, both types will be rejected and must be replaced with an autograft. "The immune system recognizes that the foreign cells do not belong to the patient," says Boyce. "Immune cells, called T-cells, will attack and destroy foreign cells in the grafts."

Grafts may not be necessary for partial-thickness burns, such as those suffered by Darren Benton; cellular wound dressings are more commonly used. "Almost 80 percent of burns in children are partial thickness," says Martin Eichelberger, M.D., director of emergency trauma and burn services at Children's Hospital in Washington, D.C., where Darren was treated. "The largest volume is from scalding."

Since the introduction of the cellular wound dressing TransCyte, Children's Hospital has used it to treat several hundred children, says Eichelberger. "It's changed our entire paradigm of care for partial thickness burns in children. The mean length of stay used to be 14 days; it's now down to one to two days." Before cellular wound dressings, when gauze was the traditional wound treatment, the pain could be so intense that the patient had to be sedated with morphine or another painkiller just to change the dressing, says Eichelberger. The development of advanced wound dressings such as TransCyte and Integra have changed that. "We're doing fewer skin grafts and we've cut our utilization of morphine by almost 80 percent," he says.

Types of Cellular Wound Dressings

Biobrane and Integra were the first FDA-approved biologically based wound dressings. Biobrane is a temporary dressing for a variety of wounds including ulcers, lacerations, and full-thickness burns. It may also be used on wounds that develop on donor sites — the areas from which healthy skin is transplanted to cover damaged skin. Made by Bertek Pharmaceuticals, Research Triangle Park, N.C., Biobrane uses an ultrathin silicone film and nylon fabric, which is partially imbedded into the film. The nylon material contains a gelatin derived from pig tissue that interacts with clotting factors in the wound. Biobrane is trimmed away as the wound heals or until autografting becomes possible.

Integra Dermal Regeneration Template was approved in 1996 to treat full-thickness and some partial-thickness burns. Made by Integra LifeSciences Corp., Plainsboro, N.J., Integra is a two-layer membrane. The bottom layer, made of shark cartilage and collagen from cow tendons, acts as a matrix onto which a person's own cells migrate over two to three weeks. The cells gradually absorb the cartilage and collagen to create a new dermis, or "neo-dermis." This bottom layer is a permanent cover. The top layer is a protective silicone sheet that is peeled off after several weeks. A very thin layer of the person's own skin is then grafted onto the neo-dermis.

Both Biobrane and Integra use animal tissue; the more recently approved cellular wound dressings are made with human tissue. One of these products is OrCel, made by Ortec International Inc. of New York. Approved by the FDA in 2001 to treat donor sites in burn patients, OrCel is made of living human skin cells grown on a cow collagen matrix. OrCel was also approved the same year to help treat epidermolysis bullosa, a rare skin condition in children.

About the Author

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