Therapeutic dressings to enhance burn wound repair and regeneration are required. Silk fibroin (SF), a natural protein, induces cell migration and serves as a biomaterial in various dressings. SF dressings usually contain α-helices and β-sheets. The former has been confirmed to improve cell proliferation and migration, but the wound healing effect and related mechanisms of β-sheet SF remain unclear. We investigated the effects of β-sheet SF in vivo and in vitro. Alcohol-treated α-helix SF transformed into the β-sheet form, which promoted granulation formation and re-epithelialization when applied as lyophilized SF dressing (LSFD) in a rat burn model. Our in vitro results showed that β-sheet SF increased human dermal fibroblast (HDF) migration and promoted the expression of extracellular matrix (ECM) proteins (fibronectin and type III collagen), matrix metalloproteinase-12, and the cell adhesion molecule, integrin β1, in rat granulation tissue and HDFs. This confirms the role of crosstalk between integrin β1 and ECM proteins in cell migration. In summary, we demonstrated that β-sheet SF facilitates tissue regeneration by modulating cell adhesion molecules in dermal fibroblasts. LSFD could find clinical application for burn wound regeneration. Moreover, β-sheet SF could be combined with anti-inflammatory materials, growth factors, or antibiotics to develop novel dressings.

Impaired wound healing is an ongoing issue that cancer patients undergoing chemotherapy or radiotherapy face. Our previous study regarding lung-cancer-associated pleural fluid (LCPF) demonstrated its propensity to promote endothelial proliferation, migration, and angiogenesis, which are crucial features during cutaneous wound healing. Therefore, the current study aimed to investigate the effect of pleural fluid on cutaneous wound closure in vitro and in vivo using HaCaT keratinocytes and a full-thickness skin wound model, respectively. Both heart-failure-associated pleural fluid (HFPF) and LCPF were sequentially centrifuged and filtered to obtain a cell-free status. Treatment with HFPF and LCPF homogeneously induced HaCaT proliferation with cell cycle progression, migration, and MMP2 upregulation. Western blotting revealed increased PI3K/Akt phosphorylation and VEGFR2/VEGFA expression in HaCaT cells. When treated with the PI3K inhibitor, LCPF-induced keratinocyte proliferation was attenuated with decreased pS6 levels. By applying the VEGFR2 inhibitor, LCPF-induced keratinocyte proliferation was ameliorated by pS6 and MMP2 downregulation. The effect of LCPF-induced cell junction rearrangement was disrupted by co-treatment with a VEGFR2 inhibitor. Compared with a 0.9% saline dressing, LCPF significantly accelerated wound closure and re-epithelization when used as a dressing material in a full-thickness wound model. Histological analysis revealed increased neo-epidermis thickness and dermis collagen synthesis in the LCPF-treated group. Furthermore, LCPF treatment activated basal keratinocytes at the wound edge with the upregulation of Ki-67, VEGFA, and MMP2. Our preliminaries provided the benefit of wet dressing with pleural fluid to improve cutaneous wound closure through enhanced re-epithelization and disclosed future autologous application in cancer wound treatment.

Delayed re-epithelialization caused by persistent inflammation and impaired keratinocyte function is a major obstacle in chronic wound healing. Resolvin E1 (RvE1), an omega-3 fatty acid-derived specialized pro-resolving mediator, is known for its anti-inflammatory actions. However, its direct effects on keratinocyte-mediated wound repair remain largely unknown. In this study, we investigated whether RvE1 promotes cutaneous wound healing by modulating keratinocyte proliferation, migration, and repair-associated signaling pathways. RvE1 significantly enhanced HaCaT keratinocyte proliferation, accompanied by increased phosphorylation of AKT, mTOR, and eIF4EBP1, as well as upregulation of cyclin D1, indicating activation of the AKT/mTOR pathway and cell cycle progression. RvE1 also accelerated scratch wound closure and induced an epithelial–mesenchymal transition-like phenotype, characterized by reduced E-cadherin expression and increased Snail and Twist protein levels. RNA sequencing (RNA-seq) revealed that RvE1 upregulated genes associated with wound healing, cell migration, epithelial–mesenchymal transition, and skin formation, including WNT3A, TRPV1, TXNIP, and KRT10. Furthermore, RvE1 activated Wnt/β-catenin signaling. Pharmacological inhibition of AKT, mTOR, or Wnt signaling abolished RvE1-induced keratinocyte proliferation and/or migration, confirming the functional involvement of these pathways. In addition, RvE1 reduced intracellular oxidative stress in keratinocytes. Topical administration of RvE1 accelerated wound closure in streptozotocin (STZ)-induced diabetic mice. Collectively, these findings demonstrate that RvE1 directly promotes keratinocyte proliferation, migration, and re-epithelialization through AKT/mTOR and Wnt/β-catenin signaling, supporting its therapeutic potential for chronic wound repair.