Effect of All-trans Retinoic Acid on Panniculus Carnosus Muscle Regeneration in Fetal Mouse Wound Healing

Background: The dermal panniculus carnosus (PC) muscle is critical for wound contraction in lower mammals and is a useful model of muscle regeneration owing to its high cellular metabolic: turnover. During wound healing in mice, skin structures, including PC, are completely regenerated up to embryonic day (E) 13, but PC is only partially regenerated in fetuses or adult animals after E14. Nevertheless, the mechanisms underlying wound repair for complete regeneration in PC have not been fully elucidated. We hypothesized that retinoic, acid (RA) signaling, which is involved in muscle differentiation, regulates PC regeneration. Methods: Surgical injury was induced in ICR mice on E13 and E14. RA receptor alpha (RAR alpha) expression in tissue samples from embryos was evaluated using immunohistochemistry and reverse transcription-quantitative polymerase, chain reaction. To evaluate the effects of RA on PC regeneration, beads soaked in alltrans RA (ATRA) were implanted in E13 wounds, and tissues were observed. The effects of RA on myoblast migration were evaluated using a cell migration assay. Results: During wound healing, RAR alpha expression was enhanced at the cut surface in PCs of E13 wounds but was attenuated at the cut edge of E14 PCs. Implantation of ATRA-containing beads inhibited PC regeneration on E13 in a concentration-dependent manner. Treatment of myoblasts with ATRA inhibited cell migration. Conclusions: ATRA inhibits PC regeneration, and decreased RAR alpha expression in wounds after E14 inhibits myoblast migration. Our findings may contribute to the development of therapies to promote complete wound regeneration, even in the muscle.