Fig. 3. CRC-secreted exosomal miR-21-5p induces angiogenesis and vascular permeability in vivo.

A Expression of miR-21-5p in circulating exosomes extracted from the serum of mice bearing SW480/mock or SW480/miR-21-5p tumors. Mean ± SEM are provided (n = 5 mice per group). B Intestinal and hepatic metastatic nodules after SW480/mock or SW480/miR-21-5p cells were injected in the cecal mesentery of nude mice for two months. Yellow arrow points at primary tumor, while red arrows point at metastatic nodules. Metastatic tumor tissues (T) and normal tissues (N) were observed. Scale bars represent 100 µm. The number of intestinal and hepatic metastatic nodules per mouse was counted under the microscope. Mean ± SEM are provided (n = 5 mice per group). C Introtumoral microvessel density in primary and metastatic tumors after SW480/mock or SW480/miR-21-5p cells were injected in the cecal mesentery of nude mice for two months. The number of microvessels was counted under the microscope (labeled by CD31). Scale bars represent 50 µm. Mean ± SEM are provided (n = 5 mice per group). D Effect of SW480/mock exosomes and SW480/miR-21-5p exosomes on vascular permeability of lung in nude mice to rhodamine-dextran by in vivo vascular permeability assay. Rhodamine-dextran was injected into the tail vein of nude mice pre-treated with SW480/mock exosomes or SW480/miR-21-5p exosomes. Levels of rhodamine-dextran fluorescence in tissues were quantified using Image J software and normalized to the levels of DAPI. Scale bars represent 50 µm. Mean ± SEM are provided (n = 5 mice per group). E SW480 were injected into the tail vein of nude mice pre-treated with SW480/mock exosomes or SW480/miR-21-5p exosomes. Red arrows point at lung metastatic nodules. Metastatic tumor tissues (T) and normal tissues (N) were observed. Scale bars represent 100 µm. The number of lung metastatic nodules per mouse was counted under the microscope. Mean ± SEM are provided (n = 5 mice per group). *P < 0.05, **P < 0.01, ***P < 0.001.