Fig. 7.

Keratinocyte to macrophage cross talk: transport of miR-21 via exosomes. a, b Day 5 wound macrophages harvested from pOBCol3.6GFPtpz transgenic mice were treated with exosomes derived from human keratinocytes (HaCaT) that were transfected with miR-21 or control mimic. Exosomes derived from miR-21 mimic-delivered keratinocytes induced Col1A1 promoter activity (GFP⁺ green cells), n = 5, Student’s t test p < 0.05, scale bar = 10 µm. c CD68 (macrophage, red) and FSP1 (fibroblast, green) immunostained MDM co-cultured with human keratinocytes (HaCaT) in a transwell chamber where keratinocytes-transfected miR-21 or control mimic were seeded on the transwell membrane (0.22 µm), n = 5, Student’s t test p < 0.05, scale bar = 10 µm. d Schematic representation of depletion of miR-21 from keratinocytes using Cre-recombinase under the control of keratin 14 promoter. e qRT-PCR analysis of miR-21 expression from wound fluid exosomes isolated from miR-21^fl/fl K14^Cre mice or corresponding wt (miR-21^fl/fl) mice, n = 5, Student’s t test p < 0.05. f The exosome concentration measured from human keratinocytes (HaCaT) treated with exosome inhibitor GW4869 or inflammatory cytokine TNFα, n = 6, Student’s t test p < 0.05