We take it for granted that cuts, bruises, and scrapes will heal over time, but chronic, nonhealing wounds are a major health problem for millions of people, and the slow pace of normal wound healing leaves the body open to life-threatening infections. Researchers at Tufts University are developing agents that, applied to open sores, could someday help chronic wounds heal successfully, and speed the normal healing process.
The wound-healing agents target angiogenesis, the process of blood vessel growth. "If you can't build new blood vessels, it's virtually impossible to heal," says Ira Herman, the project's leader and director of the Tufts Center for Innovations in Wound Healing Research. When tissue is damaged, cells migrate into the wounded region and then proliferate to form new vessels that supply oxygen and nutrients to the upper layer of skin. This is one of the processes that stall in chronic wounds.
Two decades ago, Herman and colleagues first showed that an enzyme called collagenase, produced by the bacterium Clostridium histolyticum, could promote the healing process in cultured cells and animals. When added to cultured cells, it spurred the cells to crawl and grow faster. "It essentially created track stars out of laggards," Herman says. Although humans also produce collagenase, the bacterial enzyme was more effective. The enzyme digests collagen, creating small protein fragments called peptides. The researchers believe that the peptides created by the bacterial enzyme cause a more robust response from cells.