MSC-derived exosomes suppress angiogenesis <i>in vivo</i>.

<p>(A) BALB/c mice received subcutaneous injections of 100 μl PBS per mouse containing 2×10⁵ 4T1 cells alone or 2×10⁵ 4T1 cells mixed with 100 μg of MSC-derived exosomes or 2×10⁵ 4T1 cells mixed with 200 μg of MSC-derived exosomes. The tumor sizes of mice in the groups were measured with a caliper three times a week from 20 days after tumor challenges. (B) The tumor weight was measured. (C) VEGF mRNA expressions in tumor tissues were analyzed by using qRT-PCR. (D) Immunohistochemical features of the tumor tissues were shown. Formalin-fixed paraffin sections were stained with anti-VEGF and anti-CD31 antibodies. (E) The mean number of vessels in tumor histologic sections was quantified. The values are presented as the mean ± SD; n = 4 for each group. Significant differences were evaluated using an unpaired two-tailed Student's t-test. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001 compared with control.