Inspired by the superfast wound closing process in human embryos, a new, Jell-O–like wound dressing can contract in response to the skin’s heat, drawing the edges of wounds together for quicker, safer healing. So far, researchers have tested the material only in mice. If the new bandage works as well in people, it could offer new treatment options for everything from minor wounds to chronic injuries.
“I think this is a breakthrough in general, in wound management,” says Mohsen Akbari, a bioengineer at the University of Victoria in Canada who was not involved with the study.
Traditional wound dressings like gauze and cloth bandages heal passively by keeping skin moist and holding any medicines close to the injury. The new bandage instead uses temperature-sensitive materials to draw together wounded tissue and silver nanoparticles to kill harmful microbes. “This is more of an active healing,” says Serena Blacklow, a bioengineer in medical school at the University of California, San Francisco, and one of the paper’s co–first authors.
The project began as Blacklow’s undergraduate thesis project at Harvard University. She and David Mooney, a bioengineer there, wanted to create a tough, adhesive wound dressing that could facilitate fast, safe healing for wounds large and small. They were inspired by the seamless and scar-free healing process scientists have observed in animal embryos.
In adult wounds, skin cells called keratinocytes slowly crawl across the injury to cover the wounded area. But when an embryo is wounded in the lab, it heals quickly and efficiently as thin filaments of a protein called actin quickly draw the edges of the wound together like a purse string.
With this in mind, Blacklow and her colleagues began with a gellike substance from seaweed called alginate. To make it contract in response to heat, they mixed in a widely used temperature-sensitive polymer that shrinks at about 32°C. (Human skin typically has a temperature of 37°C.) The shrinking action pulls together the skin beneath, drawing in the edges of the wound.
Once they had this temperature-responsive gel, the researchers needed to make sure it would stick to both healthy and wounded skin. They solved this problem using another material from the ocean: chitosan, a long, linear sugar molecule from the hard outer skeleton of shellfish. Chitosan penetrates both the skin and the hydrogel, linking them, whereas other bonding agents fuse them together with even more sticking power. Thanks to these ingredients, the gel is more than 17 times as sticky as a Band-Aid, ensuring it does not peel away from the wounded area.
To give the bandage antimicrobial properties, the researchers added silver nanoparticles. The particles stay in the gel while releasing a steady stream of silver ions, which are deadly to most infection-causing bacteria. The team then tested the bandage on wounded mice, which healed far more quickly with the bandage than without: Wounds closed halfway in less than 5 days versus a week or more for untreated wounds, the team reports today in Science Advances.
The gels are also relatively cheap compared with many alternatives. The raw materials to create the gel cost about $0.14 per bandage. To make a similar-size piece of Apligraf, a commercially available wound healing treatment made of living cells, the materials cost about $154.
Akbari is interested in seeing the effects of this bandage on diabetic wounds, which heal differently from normal wounds. In diabetes, cell growth slows and blood flow to extremities is reduced. The bandage has a long way to go before it could hit the market. The researchers plan to test the technology on other animals before they seek Food and Drug Administration approval.