MMP2 and neuroblastoma: To mimic metastatic colonization in the CHT and investigate the effects of NB-derived EVs on the CHT, we injected the EVs in the blood circulation of Casper zebrafish embryos at 48 hpf, isolated CHT tissues at 24 hpi (Fig 6A), and analyzed the expression of the inflammatory chemokine cxcl8b [34], and the matrix metalloproteinase-9 (mmp-9) and mmp-2, which correlate with neuroblastoma metastasis and progression (Fig 6B) [35–38].