Skin Burn Treatments

by Food and Drug Administration (FDA)

When Darren Benton leaned over to light a homemade firecracker a few days before the Fourth of July in 2000, all he was expecting was a sizzle and a loud noise. But what he got was a flash fire that burned 90 percent of his face.

"I didn't feel anything at first," says Darren. But after looking at himself in the mirror, he got very scared. The 13-year-old's face was completely black, and his right hand and knee also were burned.

Darren's parents rushed him to the hospital. Two days later, after the swelling from his burns went down, surgeons at Children's Hospital in Washington, D.C., anesthetized Darren, scrubbed the dead skin off, and gently applied a wound dressing made of human cells and synthetic material.

For several days afterward, Darren stared out of two small eye slits cut in the bandages that swathed his face to hold the wound dressing in place. He sipped liquid food through a straw poked into another small slit in the bandages.

The surgeons couldn't predict whether his face would be scarred or discolored, says Darren's mother, Patricia Benton. "Children's Hospital hadn't been using [the wound dressing] very long, and they had never used it on a child's face, but they were very positive."

Darren left the hospital after a week, and six months later, he had "completely healed," says Bruce Benton, Darren's father. Except for the loss of a few freckles on the redheaded boy's face and a slightly paler color, "it was as if nothing had happened," he says. "It was a miracle," adds Darren's mother.

The skin covering used on Darren, called TransCyte, is one of several cellular wound dressings approved by the Food and Drug Administration. These products are helping to transform the treatment of burns and chronic wounds by decreasing the risk of infection, protecting against fluid loss, requiring fewer skin grafts, and promoting and speeding the healing process.

Each year, about 45,000 Americans are hospitalized for burn treatments and 4,500 deaths occur from fire and burns, according to the American Burn Association (ABA). Twenty years ago, burns covering half the body were routinely fatal, but today, even people with extensive and severe burns have a good chance of survival, says the ABA. Essential to survival is the process of quickly removing dead tissue and immediately covering the wound.

Surgeons discovered many years ago that dead tissue was a breeding ground for bacterial infections, says Charles Durfor, Ph.D., a chemist in the FDA's Plastic and Reconstructive Surgery Devices Branch. "So there was a tremendous advance in surgical care of burns when they started cutting off that dead tissue. All of a sudden the survivability rate went way up."

But once the dead skin has been removed, the blood and fluids that the skin holds within the body start evaporating and weeping, says Phillip Noguchi, M.D., director of the FDA's Division of Cellular and Gene Therapies. "People literally can dehydrate and die from exposure."

This is where the cellular wound dressings come in. "They provide a cover that keeps fluids from evaporating and prevents blood from oozing out," says Noguchi. "And some of these products grow in place and expand much like your own skin would do when you heal."

Is it Really Skin?

As the largest organ of the body, skin protects our internal organs and tissues from toxins, disease-carrying bacteria and viruses, bumps and bruises, and extreme heat and cold. Skin has a sensory function, too. Nerve endings near the surface give us a sense of touch and the ability to feel sensations such as hot and cold.

Two layers make up the skin: the epidermis, which is the thin top layer of tissue, and the dermis, which is the thicker bottom layer. The outermost surface of the epidermis is a tough, protective coating of dead cells called keratinocytes. Underneath these dead cells are live keratinocytes, which divide and replenish the outer layer as the dead cells fall off. Also found within the epidermis are cells that give skin its color (melanocytes) and cells that help protect the body against infection (Langerhans' cells).

The dermis, the lower layer of skin, consists of cells called fibroblasts. These fibroblasts produce collagen, the most common protein in the body, which gives structure and flexibility to the skin. The dermis also contains blood vessels, nerves, hair follicles, and oil and sweat glands.

Cellular wound dressings are sometimes called "artificial skin" or "skin substitutes," but FDA scientists prefer to avoid these labels. "Although they may look and feel like skin, these products do not function totally like skin," says Durfor. "Unlike real skin, they are missing hair follicles, sweat glands, melanocytes and Langerhans' cells."

In some respects, cellular wound dressings try to simulate the two layers of real skin. Some have a synthetic top layer structured like an epidermis. Over time, it peels away or is replaced with healthy skin through skin grafting. The bottom layer usually consists of a scaffold, or matrix, which supports cells that help promote the growth of new skin. Blood vessels, fibroblasts, and nerve fibers from healthy tissue surrounding a burn or wound cross into the matrix to mix with the wound dressing's cells. The matrix eventually disappears as a new dermis forms.

"No one has a full understanding of how these products work," says Durfor. "How they are involved in wound repair is a subject of great scientific interest."

"We do know that they promote a higher rate of healing," says Stephen Rhodes, head of the FDA's Plastic and Reconstructive Surgery Devices Branch. "More patients heal with these devices than with the standard of care, which includes compression bandages and gauze."

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.