Optimal skin regeneration after full thickness thermal burn injury in the spiny mouse, Acomys cahirinus.

The spiny mouse, Acomys cahirinus, shows remarkable regenerative abilities after excisional skin wounding by regrowing hair, sebaceous glands, smooth muscle, skeletal muscle and dermis without scarring. We have asked here whether this same regeneration can be seen after full thickness thermal burn injuries. Using a brass rod thermal injury model we show that in contrast to the lab mouse, Mus musculus, which forms a thick scar covered by a hairless epidermis, the spiny mouse regenerates all the tissues injured - skeletal muscle, dermis, hairs, sebaceous glands such that the skin is externally indistinguishable from its original appearance. Re-epithelialization is faster in Acomys than in Mus but ingression and proliferation of dermal fibroblasts is the same in both species. After 3 weeks the wound epithelium of Acomys has developed a covering of new hair follicles in contrast to Mus. The skeletal muscle of the panniculus carnosus in Mus shows some regeneration but it is incomplete and fibrotic whereas the Acomys muscle is replaced perfectly. There are differences in the macrophage profiles which invade the damaged tissues such as the absence of F4/80 or MOMA-2 +ve cells in Acomys which likely reflect different cytokine profiles resulting from the same injury in these two species.