Syringin (Sinapyl Alcohol 4-O-Glucoside) Improves the Wound Healing Capacity of Fibroblasts and Keratinocytes In Vitro.

Wound healing is a complex process in which TGFβ plays a key role. Previous studies have shown that syringin, a phenylpropanoid glycoside present in lilac bark (Syringa vulgaris L.), stimulates TGFβ expression in human monocyte-derived macrophages in addition to inhibiting the secretion of pro-inflammatory cytokines. Here, we investigated the effect of syringin on migration, invasion, and TGFβ production, as well as the effect on the release of pro-inflammatory cytokines in human dermal fibroblasts (NHDF) and keratinocytes (HaCaT) and its mechanism of action. NHDF and HaCaT cells were treated with the tested compound (12.5-100 µM), and a scratch assay was performed. The effect of migration using modified Boyden chambers was analyzed. TGFβ and IL-6 release were also assessed using ELISA kits. Cell proliferation was assessed using MTT and BrdU incorporation tests, while cytotoxicity was assessed using a neutral red uptake test. Smad2 and Smad3 phosphorylation were assessed using Western Blotting. ACTA2, COL1A1, and TIMP3 expression was analyzed using qPCR. Cells treated with syringin showed an increase in invasion potential in the scratch assay. A significant increase in skin fibroblast migration through the porous membrane was also observed. Syringin increased TGFβ release and inhibited IL-6 release by NHDF and HaCaT cells. No effect of syringin on cell proliferation or cytotoxic effects was observed. Western blot analysis showed significant activation of Smad2 and Smad3 in the presence of syringin in NHDF cells, but not in HaCaT. Quantitative PCR analysis revealed a strong increase in ACTA2 and COL1A1 gene expression in fibroblast cells treated with syringin. The present study demonstrated that syringin present in S. vulgaris stem bark increased dermal fibroblasts and keratinocytes' wound healing function through activation of cell migration.