## 4 Discussion
In this study, DEX delayed the healing process and decreased the level of collagen fibers and the density of capillaries in a mouse excisional wound model. Moreover, the expression of TGF-\(\beta\) in the wound sites was also reduced in the DEX-treated mice. Puerrin treatment improved these phenomena, suggesting that Puerrin might accelerate wound healing by promoting collagen deposition and angiogenesis. Keratinocytes, the most predominant component of the epidermis, play an essential role in the wound healing process, particularly in the proliferation phase [35]. The proliferation phase includes granulation tissue and re-epithelialization. Granulation tissue formation consists of collagen synthesis by fibroblasts and neovascularization by endothelial cells, whereas re-epithelialization is characterized by the proliferation and migration of keratinocytes [36]. In this study, DEX inhibited wound healing significantly in the mouse model (day 7, day 14) and suppressed the proliferation and migration in HaCaT keratinocytes. The Puerrin treatment recovered these impairments. Puerrin promoted keratinocyte proliferation by increasing Ki67, K16, and K17 expressions and switching the cell cycle from the G1 to the S phase in DEX-treated HaCaT cells. This result was consistent with a previous study showing that Puerrin enhanced the proliferation and differentiation of osteoblasts to stimulate bone regeneration [37]. Puerrin also recovered DEX-impaired migration in HaCaT cells in the scratching sound healing assay. In contrast to the inhibitory effects of Puerrin on the proliferation and migration in cancer studies [38; 39], this report was the first indicating that Puerrin could promote proliferation and migration in keratinocytes, improving the wound healing process in various DEX-treated models. The underlying mechanisms mediating the effects of Puerrin were investigated. ERK and Akt were critical signaling pathways that regulated a range of cellular processes, such as cell growth, proliferation, differentiation, apoptosis, and mobility [40; 41]. The roles of ERK and Akt in keratinocyte proliferation and migration were demonstrated [42]. In the current study, DEX suppressed ERK and Akt phosphorylation, which were restored by a Puerrin treatment. This result was consistent with a previous study indicating that icariin, a flavonoid from Herba Epimedii (the aerial parts from several _Epimedium_ species), enhanced the migration and proliferation of keratinocytes via the ERK and Akt pathways [43]. Furthermore, ERK and Akt inhibitors repressed Puerrin-induced proliferation and migration in DEX-treated HaCaT cells, highlighting the crucial roles of the ERK and Akt signaling pathways in mediating the effects of Puerrin. This study had some limitations. Wound healing is a complicated process with the involvement of various cellular components and overlapping events. This study only demonstrated the effects of Puerrin on keratinocyte proliferation and migration. On the other hand, puerarin may affect other cell types, such as fibroblasts and endothelial cells. Therefore, further studies will be needed to prove the beneficial effects of puerarin on wound healing and to investigate other mechanisms mediating these effects.