Fig. 9

E. coli murine mastitis treated by intramammary (IMM) infusion of bMSC. Lactating BALB/c mice were challenged by IMM infusion of 10⁴ CFUs of E. coli P4-GFP bacteria and treated 6 h later by IMM infusion of 200,000 bMSC. Mammary tissues were harvested 24 h after challenge and analyzed using fluorescence microscopy (A-C) and gene expression using qPCR (D). Mastitis is characterized by massive infiltration of neutrophils into alveolar and tubular milk spaces (white arrows in A-C) and increased gene expression of inflammation markers (D). Representative images of fluorescence staining using DAPI (blue) phalloidin (red in A-B, white in C), and anti-murine CD45 antibodies (green in B). Fluorescing GFP bacteria interacting with neutrophils and epithelial cells are visible in C. CFSE-labelled bMSC are visible in the lumen of a large milk tubule (green in A) and boxed area is enlarged and better visible in Supplementary Figure S7. Using RT-qPCR the relative expression of Cxcl1 (KC), Cxcl2 (MIP2), TNFɑ, IL1β, and Icam1 genes was quantified relative to RNA samples extracted from the mammary tissues of lactating normal age-matched control mice (D). Scale bars 50 µm (A-B) and 20 µm (C)