Fig. 2

Systemic administration of bacterial extracellular vesicles induces effective antitumor responses in multiple tumors. a Tumor volume of mice measured after the subcutaneous injection of MC38 murine adenocarcinoma (total n = 14 mice per group, two independent experiments). E. coli ∆msbB OMVs (5 μg in total protein amount) were injected intravenously four times from day 7 with 3 days intervals. b, c To induce spontaneous lung metastasis, highly metastatic 4T1 murine carcinoma cells and B16BL6 melanoma cells were subcutaneously injected to the right flank of the mice (total n = 12 mice per group, two independent experiments). PBS or E. coli ∆msbB OMVs (5 μg in total protein amount) were intravenously treated for four times with 3 days intervals from day 7. At day 22, mice were killed and the number of colonies spontaneously metastasized in the lungs for 4T1 b and B16BL6 c tumors were counted. d, e Tumor volume of mice bearing CT26 tumor of mice intravenously injected with four doses of 5 μg of Gram-negative E. coli W3110 wild type- and Salmonella enterica wild type-derived OMVs. d Gram-positive bacteria Staphylococcus aureus wild type- and lipoteichoic acid (LTA) mutant-derived extracellular vesicles (EVs), and Lactobacillus acidophilus wild type-derived extracellular vesicles (EVs), e (n = 5 mice per group). Data are presented as the mean ± SD from a representative experiments. *P < 0.01 and **P < 0.001, respectively, analysed by unpaired Student’s t-test b, c or two-way ANOVA a, d, e. Bonferroni post test was applied to compare each treated group with PBS group d, e