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Saved by a Skin

More Than Skin Deep

Beauty, as they say, is more than skin deep. But for severe burn victims, that thin layer of skin stretches precariously between recovery and disability or death.

Our skin is not merely a convenient packaging to cover up our insides, it protects our bodies from dangerous bacteria and viruses, regulates body temperature and sensation, seals in our vital fluids, and immune cells in the skin help the body prevent and fight disease. Our skin consists of three layers, making up a highly dynamic network of cells, nerves, and blood vessels.

When you get burned, all of these protections are in jeopardy. People with severe burns face their greatest risk from infection and from rapid, life-threatening fluid loss, which jolts the body into shock and massive organ failure.

Burn-induced skin loss can give bacteria and other microorganisms easy access to the nutrient-rich fluids that course through the body, while at the same time allowing these fluids to leak out rapidly. Enough fluid loss can thrust a burn or trauma patient into shock, so doctors must replenish skin lost to severe burns as quickly as possible.

In the case of burns covering a significant portion of the body, surgeons must do two things fast: strip off the burned skin, then cover the unprotected underlying tissue. These important steps in the immediate care of a burn patient took scientists decades to figure out, as they performed carefully conducted experiments on how the body responds to burn injury.

Ideally, surgeons obtain skin grafts from an unburned area of skin elsewhere on the body. But when the burn is severe and covers 80 to 90 percent of a person's body surface, there is not enough skin to use for this purpose.

What is a Skin Graft?

There are two types of skin grafts:

• 1) Autologous
  An autologous skin graft transfers skin from one part of the body to another part of the body.
• 2) Allograft
  An allograft transfers skin from another person, sometimes even a cadaver (a dead person). Allografts offer only temporary cover, as they are quickly rejected by a person's immune system.

How are Skin Grafts Made?

New epidermal skin can be produced by taking cells from a non-burned epidermal layer of skin, growing them into large sheets of cells in a laboratory, then placing the cell sheets on top of Integra ®. Scientists do not yet know how to grow the lower, dermal layer of skin in the lab.

Treating Severe Burns with Artificial Skin

In the early 1980s, researchers doing this work developed the first version of an artificial skin covering called Integra ® Dermal Regeneration Template ™, which doctors use to drape over the area where the burned skin has been removed.

What is Integra ®?

Integra ® is an artificial substance that contains no living components. It is not designed to be a replacement skin. Rather, Integra ® supplies a protective covering and a pliable scaffold onto which a person's own skin cells can regenerate the lower, dermal layer of skin destroyed by burn.

Integra ® consists of two layers, just like living skin. The bottom layer, which is designed to regenerate the lower layer of real skin, is composed of a matrix of interwoven bovine collagen (a fibrous cow protein) and a sticky carbohydrate (sugar) molecule called glycosaminoglycan that mimics the fibrous pattern of the bottom layer of skin. This matrix then sticks to a temporary upper layer: a medical-grade, flexible silicon sheet that mimics the top, epidermal layer of skin. Integra ® looks somewhat like clear cellophane wrap.

How Does Artificial Skin Help a Burn Victim?

After first removing tissue destroyed by a severe burn, a burn surgeon drapes Integra ® over a wounded area of skin and leaves it there for 2 to 4 weeks, during which time the burn victim's own cells climb onto the matrix and grow a new dermis. Surgeons then remove the top layer of Integra ® and apply a very thin sheet of that person's own epithelial cells. Over time, a normal epidermis (except for the absence of hair follicles) is reconstructed from these cells.

Who Makes Integra ®?

Integra ® was originally licensed, tested, and produced by Marion Laboratories of Kansas City, Missouri. It is now manufactured and sold by Integra LifeSciences Corporation of Plainsboro, New Jersey.

Thanks in large part to Integra ® and to decades of basic, NIGMS-supported research on burns and wound healing, the grim prognosis faced by burn patients has brightened significantly. Twenty years ago, patients with severe burns over half their bodies rarely survived. Today, those patients usually recover - and so, incredibly, do some patients with severe burns over 90 percent of their bodies.

NIGMS-funded (National Institute of General Medical Sciences) scientists continue to improve upon Integra ® Dermal Regeneration Template ™. Today, Integra ® Dermal Regeneration Template ™ is now the top-selling skin substitute used to treat burn patients throughout the world.

References:
National Institute of General Medical Sciences (NIGMS)
2006
July 2008
publications.nigms.nih.gov
www.nigms.nih.gov