African spiny mice can shed damaged skin tissue and grow it back again. This discovery opens up possibilities to study models in regenerative medicine, a new study says.

A study was carried out on two species of African spiny mice (Acomys kempi and Acomys percivali) by researchers from the University of Florida (UF). Ashley W. Seifert, a postdoctoral researcher in UF's biology department, was studying scar-free tissue healing when a colleague told him about an African mice species that is capable of autotomy, a defense mechanism in which an animal severs a part of its body to escape being preyed upon by a predator.

Animals such as lizards and salamanders are known to regrow parts of their bodies after an injury, but such ability to regenerate body parts after autotomy was not studied in mammals.

"Autotomy in skinks, geckos and some salamanders is well known. But it is very rare in mammals, and so far we've only seen it in a few rodents that can jettison their tail," said Seifert. According to Seifert, it's not just the skin that comes back but even hair follicles and cartilage are regenerated.

Seifert studied the mice at Mpala Research Centre near Nairobi, Kenya. To study the rodents' capability of regrowing lost parts, he punctured holes in the mice's ears with a 4mm biopsy punch to see if the animal grew back the ear. Surprisingly, it did.

"The results were astonishing. The various tissues in the ear grew back through formation of blastema-like structures - the same sort of biological process that a salamander uses to regenerate a severed limb," he said.

Human skin also regenerates to some extent after an injury, but due to the presence of a certain molecule (Collagen I) in the body, scar tissue forms at the site of injury. The African spiny mouse, on the other hand, has more of a molecule called Collagen III that promotes growth of normal tissue, the Los Angeles Times reports.

"It could represent a new model system for skin wound healing and tissue regeneration in humans," said Ken Muneoka, a professor of cell and molecular biology at the Tulane University who was not involved with the study.

"It is truly exciting to discover that these mammals are capable of losing and regrowing complex tissue in such an efficient manner. It's another 'gripping' example of how organisms can evolve alternative, adaptive traits not by inventing new structures or pathways but by modifying existing structures," said Tara Maginnis, evolutionary biologist from the University of Portland in Oregon, reports Science. Maginnis was not involved in the present study, which is published in the journal Nature.