Skin regeneration after serious wounds often takes a long time. When skin grows back after an injury, a scar, marking the place of the once missing skin, can often remain.

However, cell growth stem cells and their regulating proteins can potentially hold the key to scar avoidance and faster wound repair.

During an injury, cells are very likely to die because they are damaged or no longer connected to the rest of the body. The cellular process of death is called apoptosis, a highly coordinated cellular event where many other proteins and molecules are involved in allowing a cell to die and recycle the parts that once made it up. Apoptosis is used throughout the body at various times, but during injury, apoptosis patterns are especially noteworthy.

Regulatory protein that stop apoptosis, or cell death, are called inhibitors of apoptosis proteins (IAP). This process performed by IAP can be dangerous, as it can lead to cancers and tumor development.

However, in a new study, researchers used stem cells combined with IAPs to improve wound repair and skin regeneration in mice.

Researchers studied mice whose back skin had been abraded away. When they turned off the IAP, they observed that within five days, the wound size was reduced by 80 percent. The skin had not quite regenerated, but there were clear signs of repair. In mice with functional IAP, meaning the protein could not prevent cell death, wound size only improved by 10 percent after five days. The results seen after allowing cell death to occur by turning on the IAP was promising. The great reduction in wound size when cell death was blocked indicated that cell death is involved in preventing wound healing and if cells are allowed to grow, wound repair is more likely to happen quickly.

Quicker wound repair is important. Even if actual healing is slow, repair of the skin surrounding the injury is important for the prevention of infections.

The researchers also wanted to see whether the addition of stem cells could speed up the process of wound healing, in addition to turning off cell death capabilities. When hair follicle stem cells, stem cells that are normally at the surface of skin, were added to mice whose cell death was impaired, 3.5 times more cells regenerated in seven days, compared to those who were not given the stem cells. This rapid regeneration and healing prevented or minimized scaring. Those with cell death capabilities intact had large scars, up to 2 centimeters wide, while those without the cell death capability had scars smaller than half of a centimeter wide.

The use of stem cells and apoptosis blockers appears to be a promising therapy for mice with injuries. However, it should be noted that the older a mouse was, the more days it took for their skin to regenerate; the older mice took up to 11 days to heal. Similarly, without the addition of stem cells, there was not as much skin regeneration.

While the use of cell death blockers and stem cell may have promising applications in mice, human trials have yet to be performed. It is unlikely that using stem cells for surface injuries will become common practice until stem cells and stem cell research can become more affordable.

Sources: Fuchs Y, Brown S, Gorenc T, Rodriguez J, Fuchs E, Steller H. Sept4/ARTS Regulates Stem Cell Apoptosis and Skin Regeneration. Science. 2013.