September 27, 2012
Scar-Free Healing Mice Offer Clues To Human Skin Repair
April Flowers for redOrbit.com - Your Universe Online
African spiny mice (genus Acomys) have brittle skin, which tears off in continuous sheets, like human skin, in order to escape predators. Some of them lose as much as 60% of the skin from their backs, which then heals rapidly, regrowing hair instead of scarring.Scientists want to figure out how this healing takes place and if it could apply to treatments for people. The study, published in Nature, says the unusual healing of these mice could offer clues to healing wounds without scarring.
Salamanders are famed for their regenerative abilities, with some of them able to regrow entire limbs. This ability has made them a focus for many researchers hoping to figure out how to reproduce the same effect in humans. The ability of mammals to regrow lost organs, however, is very limited as wounds are normally sealed with scars.
"This study shows that mammals as a group may in fact have higher regenerative abilities then they are given credit for," said Dr Ashley Seifert from the University of Florida. "These guys had been known to lose their tail, but no one had ever reported on skin dislodging from their body."
The mice healed five out of six wounds in only three days, having "completely re-epithelialized." It took another 30 days for the hair to regrow, but it was the same original color.
This process of re-epithelialization, the replacement of lost skin cells with new ones, is the key. When a wound happens, skin cells called epidermal cells "crawl" over the wound, covering it and establishing interactions to promote healing.
Skin regeneration wasn't the only trick these mice had up their sleeves, however. They were also able to regenerate hair follicles, sweat glands and cartilage from large circular holes punched in their ears.
The mice produced a blastema, or "regeneration hub," to repair the injuries. The salamander uses the same bundle of stem cells to rebuild missing body parts.
"It is thought that one of the main constraints on regenerating appendages in humans, or mammals for that fact, is the failure to form a blastema," Dr. Seifert who wants to investigate how these structures form in mice, told James Gallagher of BBC News.
The web of proteins that hold cells in place, the extracellular matrix, is another difference.
He went on to say, "These mice appear to deposit extracellular matrix into their wounds at a slower rate than mice, pigs or humans. Although many scientists are trying to speed up the healing process, our studies on spiny mice and salamanders show that slowing things down is the path towards regeneration."
Understanding the process and extending it to humans is going to be a long process.
The spiny mice have an abundance of collagen III molecule, which aids in the generation of new, normal tissue, while humans have far more collagen I, which leads to scarring.
Elly Tanaka, from the Technische University Dresden, said, "These studies suggest that the pathways leading to regeneration, at least of the skin, that are normally associated with amphibians are also accessible in mammals."
She added that harnessing the process "in a controlled manner in other wound situations may help to promote scarless healing".
Siefert and his team will continue to study the mice, creating a colony of them in the U.S. to research regeneration comparatively across different species to find a basic blueprint.