Fig. 1

Decreased RNA m⁶A modification and increased ALKBH5 expression in keratinocytes in healthy wound edges. a Generation of 5-mm diameter full-thickness skin wounds on mouse backs with the fascia (red dashed lines) below the panniculus carnosus excised to prevent wound contraction. b The gross appearance and histology of skin wounds at post wound day 2 (PWD2). The wound bed, wound edge, and adjacent normal skin were outlined and designated. Scale bar: 250 μm. c Global m⁶A levels of mRNA extracted from the skin of wound edges and adjacent normal skin were measured by m⁶A DB assays. Total RNA was determined by methylene blue staining (as a loading control). The experiments were performed in triplicate. t test, two-sided *P < 0.05. d Heatmap of m⁶A “writer” and “eraser” gene expression in wound edges and normal skin. The experiments were performed with four biological replicates. e Heatmap of m⁶A “writer” and “eraser” gene expression in the epidermis and dermis of the wound bed and wound edge according to RNA-seq data (GSE159939). f ALKBH5 expression in the skin of the wound edge was visualized by IF. Scale bar: 100 μm. g Statistical analysis of the percentage of ALKBH5⁺ keratinocytes per HPF. Wound samples were collected from four mice, and the percentage of ALKBH5⁺ cells is shown as the mean ± SD. t test, two-sided ***P < 0.001. h Representative clinical photography showing a cohort of patients with chronic wounds characterized by healed or refractory nonhealing wounds. i ALKBH5 expression in the wound edges of healed wounds, refractory wounds, and normal skin was visualized by IF. Scale bar: 100 μm. j Statistical analysis of the percentage of ALKBH5⁺ epidermal cells per HPF. The wound edges of four healed wounds, six refractory wounds, and their corresponding normal skin controls were analyzed. The percentage of ALKBH5⁺ cells is shown as the mean ± SD. One-way ANOVA, ***P < 0.001. Epi epidermis. Dotted lines denote epidermal boundaries