Biting your tongue or cheek when chewing can ruin a tasty meal. But thankfully, mouth wounds heal up fast — faster than cuts on skin — and now scientists know why. According to new research published today in Science Translational Medicine, mouths are primed for healing. The find could help researchers transfer the mouth’s curative superpowers to make skin lesions heal faster too.
Paper cuts, scraped knees and similar skin wounds take about a week to heal. But pressure ulcers, traumatic injury and surgery can take longer, sometimes months. For elderly folks who have fragile skin and those living with metabolic diseases such as diabetes, some skin lesions might not heal, leaving people vulnerable to infection and scarring.
“There is an urgent need to develop effective approaches to accelerate the healing of skin wounds,” Maria Morasso, a skin biologist with the National Institute of Arthritis and Musculoskeletal and Skin Diseases in Bethesda, Maryland, who led the new research, said in a statement.
Rather than trying to identify what goes wrong when skin wounds don’t heal well as scientists have in the past, Morasso looked for a place where wounds close up easily and quickly: the mouth.
For Morasso, it made sense that mouth injuries mend with speed. Chewing causes friction to irritate wounds, so swift healing can stop rubbing from dragging out an injury. And the mouth is full of microbes. Trauma breaks the barrier that keeps out bacteria, so it’s important to close up gaps fast for overall health.
To find out why mouth wounds heal faster than those to skin, Morasso and a team of researchers convinced 30 healthy individuals to let them take an eighth of an inch hole punch from the insides of their cheeks and the undersides of their arms. As expected, the mouth wounds closed up in a few days, but the skin wounds lingered for more than two weeks.
When the team analyzed changes in gene expression from the skin and mouth one day after inflicting the injuries, they found that wound repair genes were already turned on in the mouth. That means the mouth is ready to spring into curative action, whereas the skin takes longer to turn on repair systems before healing can begin. That might be why skin wounds heal slower than oral ones, the researchers say. Additionally, mouth cells prevented inflammation, further accelerating healing.
The researchers also identified two master-healing proteins in the mouth that help cells move in to close up wounds. When they turned on these factors in skin cells, the cells took on the healing properties of the mouth and even restored skin lesions more quickly in mice.
The researchers say the new discovery will help identify ways to pharmacologically target skins cells for faster healing.