December 24, 2021
University of Tsukuba
Keio University School of Medicine
Shinshu University
The Nippon Dental University
Utsunomiya University
In surgery and cosmetic medicine, the ideal method for healing skin wounds is considered to be regenerative treatment that leaves no scars (scar-free healing). However, tetrapods (four-limbed vertebrates), including humans, generally lose their ability to regenerate tissues and organs after metamorphosis, hatching, or birth. Therefore, this study focused on newts. Newts are known for their ability to regenerate various parts of their bodies repeatedly throughout their lives. However, little was known about skin regeneration in newts.
Using adult Japanese fire-bellied newts (Cynops pyrrhogaster), we excised full-thickness skin, including the epidermis and dermis, from various parts of the body and investigated re-epithelialization, the presence or absence of fibrosis, the recovery of skin texture, the restoration of skin appendages such as secretory glands, and the recovery of color (hue, tone, and pattern). The results revealed that adult newts regenerate scar-free skin by rapidly closing the wound with almost no increase in the division frequency of epidermal stem cells around the wound, while simultaneously suppressing the inflammatory response. Although it took time, the skin texture, appendages, and coloration also recovered. On the other hand, it became clear that the skin on the belly could not be perfectly regenerated, as the red and black pattern became different from the pattern before the injury.
As described above, even newts with their high regenerative capacity had difficulty restoring the color pattern on their bellies. However, humans do not have color patterns like those of newts. Therefore, skin regeneration in adult Japanese fire-bellied newts is considered an ideal model system for research on regenerative skin treatment for postnatal humans.
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