Each year more than 45,000 Americans suffer burns serious enough to require a hospital stay, according to the American Burn Association. While the traditional therapy of using skin grafts to cover burn sites has improved, a number of problems including scarring, infection and poor adhesion remain.
Skin grafts involve taking skin (both the upper epidermal layer and the underlying dermis) from an unburned site on the patient's body or from a cadaver and grafting it on to the burn wound,said Craig D. Woodworth, a cell biologist and associate professor at Clarkson University. Skin grafts often require multiple surgeries. Cadaver skin is scarce and can introduce disease. In the case of extensive burns, large amounts of skin can be created by isolating individual epidermal cells and then expanding their numbers in culture, but the skin simply does not look or function like normal skin. There are no hair follicles, no pores for sweating, and the pigment is often a poor match.
Woodworth is collaborating with Anja Mueller, a polymer chemist and assistant professor of chemistry at Clarkson, on research to develop an artificial skin that would heal and function like normal skin and could be used successfully for large burns or surgical reconstruction.
Our goal is to bioengineer an artificial skin scaffold that promotes tissue regeneration and even directs cell growth for hair follicles and sweat glands so that the new skin would look and feel like normal skin,said Woodworth.
Though still in its early stages, their initial research looks promising. While Woodworth focuses on isolating a combination of cytokines that will generate skin growth and promote wound healing, Mueller is creating and testing biodegradable polymers to find one that will support cell growth and regeneration.
Cytokines are naturally occurring proteins that regulate or modify the growth of specific cells. The development of skin is complex and there are hundreds of different cytokines that are made by skin cells. However, only a subset are critical for skin growth and differentiation.
An important question, then, is which cytokines are most effective in helping the graft heal and restore normal function,explained Woodworth. We are focusing on several, including EGF (epidermal growth factor) that stimulates cells to grow quickly and fill in the wound and VEGF (vascular endothelial growth factor) that stimulates blood vessel formation and nourishes the grafted skin.
Recently, Woodworth has been working in the laboratory analyzing the effects of Transforming Growth Factor-B1 (TGF-B1) on gene expression in skin cells. This cytokine regulates production of certain cell proteins, namely collagen and connective tissue proteins, associated with wound healing.
Our results show that TGF-B1 stimulates the formation of collagen, the natural scaffold for skin, by the fibroblasts, the underlying supporting cells,explained Woodworth. However, long-term expression of TGF-B1 also contributes to scarring when it is produced after the initial healing has occured. Therefore, the trick may be to turn TGF-B1 on initially, but then turn if off when the skin begins to restore normal structure and function.
Meanwhile, in her laboratory Mueller is testing biodegradable polymers in order to find the rightpolymer that will maximize the function of a bioengineered skin scaffold.