In zebrafish model, exosomes derived from either brain endothelial cells or brain tumor cells crossed the blood–brain barrier (BBB) and successfully deliver anti-cancer drugs to the brain tumors, with 4 nl of 0.2 mg/ml doxorubicin loaded in 200 μg/ml of brain endothelial cell-derived exosomes inhibiting expression of VEGF RNA more than half compared to doxorubicin-only injected brain tumor model of zebrafish [48]. Here, VEGFA is linked to brain neoplasm.