There is an interesting history of accidental discoveries regarding exceptional regeneration in mammals, such as the MRL mice that are capable of regenerating the ear tags and notches that researchers use to track mice through experiments, thereby causing some confusion. Researchers have since then spent time on attempts to identify important mechanisms by which mammalian regeneration takes the path of scarring, rather than the path of regrowth. The discovery noted here is an interesting one. The scientists involved have established a good proof of concept based on a regulator of scarring, EN1. When suppressed this leads to the complete regeneration of skin injuries without scar formation.
Skin wounds generally heal by scarring, a fibrotic process mediated by the Engrailed-1 (En1) fibroblast lineage. Scars differ from normal unwounded skin in three ways: (i) They lack hair follicles, sebaceous glands, and other dermal appendages; (ii) they contain dense, parallel extracellular matrix fibers rather than the “basket-weave” pattern of uninjured skin; and (iii) as a result of this altered matrix structure, they lack skin’s normal flexibility and strength. A successful scar therapy would address these three differences by promoting regrowth of dermal appendages, reestablishment of normal matrix ultrastructure, and
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