African rodent species resist scarring

You might be familiar with tissue regeneration in amphibians and reptiles where limbs can be fully regenerated following an injury. Until now, tissue regeneration following a wound was thought to be limited in mammals (ex: deer shed and regrow their antlers annually; some mice can regrow the tips of their fingers).

Researchers discovered that African spiny mice are able to regrow skin, complete with hair follicles, after an injury. We are not talking about simple wound healing, but actual skin regeneration without scarring. Researchers suspect this unique ability may have evolved to help them avoid predators since they are capable of shedding large patches of skin to escape. Researchers found their skin to be less elastic than laboratory mice (M. musculus), increasing its susceptibility to tearing. Sometimes the tears are so deep, the muscles below become exposed.

A transdermal injury at day 3. Figure from: Nature doi: 10.1038/nature11499

Transdermal injury at day 30. Figure from Nature doi: 10.1038/nature11499

The researchers found that epithelial cell migration to the site of injury was much faster in the African mice. The collagen fibers also organized into loose bundles, preventing scarring. In contrast, collagen fibers in laboratory mice form dense, organized bundles that promote scars. Moreover, the African mice actually regrow hair follicles, whereas laboratory mice do not. Not only can the animals regrow torn skin, but they are also able to heal holes pierced into their ears complete with cartilage, hair follicles, skin, sebaceous glands and fat without scarring, although the regrown tissue lacked muscle. This ear regeneration is regulated by specialized cells called blastema that are similar to those found in lizards capable of regrowing tails.

Researchers hope this research will help to better understand tissue regeneration, as opposed to scarring, capabilities in mammals.

This research reminds me of the futuristic technology in Star Trek episodes, where they use light to heal wounds with minimal scarring.

Source:
Seifert AW, Kiama SG, Seifert MG, Goheen JR, Palmer TM, Maden M. Skin shedding and tissue regeneration in African spiny mice (Acomys). Nature. 489:561-566, 2012.