Fig. 1

Colon cancer cell-derived exosomes inhibit the immune microenvironment of the mouse liver. (A-F) Five-week-old female BALB/c mice (n = 8 per group) were injected with 20 µg of CT-26 cell-derived exosomes (CT-26/exo), MCEC cell-derived exosomes (MCEC/exo), or PBS via the tail vein every 3 days. After 3 weeks, the mice were sacrificed, and liver tissues were collected. Immunofluorescence staining was performed to detect the number of M1 macrophages (CD86+/CD11b+) (A, B), M2 macrophages (CD206+/CD11b+) (C, D), and CD8 + T cells (E, F) in the liver tissues. Scale bar = 50 μm. (G-Q) Five-week-old female BALB/c mice (n = 8 per group) were injected with 20 µg of CT-26/exosome, MCEC/exosome, or PBS via the tail vein every 3 days. After 3 weeks of exosome treatment, luciferase-labeled CT-26 cells (1 × 10^6) were injected into the tail vein of each group. (G) Experimental protocol. On day 21 after tumor cell injection, metastasis in each group was monitored using a small animal in vivo imaging system (H, I), followed by dissection of the livers. Hematoxylin and eosin (HE) staining was used to quantify the number of metastatic nodules in the liver per mouse (J, K). Immunofluorescence staining was then performed to detect the number of M1 macrophages (CD86+/CD11b+) (L, M), M2 macrophages (CD206+/CD11b+) (N, O), and CD8 + T cells (P, Q) in the liver tissues. Scale bar = 50 μm. Data were presented as mean ± SEM (B, D, F, I, K, M, O, Q). Statistical analyses were performed with one-way ANOVA with Tukey’s test (B, D, F, I, K, M, O, Q)