Recent discoveries about how mouth injuries heal without bruising could lead to treatment methods that prevent permanent scars and improve skin appearance.

“Millions of individuals experience injuries, surgeries, burns, and various other traumas,” states Ophir Klein from Cedars-Sinai Medical Center in Los Angeles, California. “This represents a significant issue not only in cosmetic terms but also functional terms,” he adds. For instance, he mentions that a major wound can restrict leg movement due to skin tightening.

To explore this, Klein and his team took advantage of the fact that mouth wounds heal without scarring. “Injuries inside the mouth heal more quickly and with fewer scars compared to skin injuries,” he explains.

Upon investigation, the researchers created 2.5mm wide wounds both in the mouth and on the face of mice. They collected tissue samples as these wounds healed over the course of a week.

The team analyzed cells known as fibroblasts that are associated with scarring and discovered that fibroblasts in the mouth exhibited higher activity levels for genes encoding proteins such as Gas6 and Axl than those in the skin. These proteins are known to promote cell growth, migration, and survival.

The Gas6-Axl pathway seemed to inhibit the levels of a protein called FAK, which is involved in depositing proteins on wounds, leading to scar formation. “We were aware of this pathway’s existence, but its role in non-scarring wound healing was unknown,” Klein notes.

The next step for the researchers was to assess whether enhancing the Gas6-Axl pathway could minimize skin scarring. They administered a solution containing Gas6 to freshly created facial scars on mice. After two weeks, these treated wounds exhibited reduced FAK levels and fewer scars compared to those in untreated mice. “They have successfully shown that stimulating this pathway can diminish scarring,” says Jason Wong at the University of Manchester, UK.

“This is certainly a significant step towards what could be a scar-free future,” states Ines Sequeira from Queen Mary University in London. However, he cautions that further research is needed with larger animals like pigs, which have skin more similar to humans, before moving towards human trials.