Macrophages capturing physiological extracellular vesicles (EVs) that circulate in the bloodstream. Eggs obtained from Tg(mpeg1:mCherry) fish were transfected with DNA plasmids by microinjection into the yolk syncytial later (YSL) that is formed at 3-4 hpf. The caudal vein tissue of the transfected embryos at 3 dpf was imaged every minute for 30 min. YSL EVs in yellow, macrophages in magenta. (Movie: Yuya Hayashi)

Live imaging of physiological extracellular vesicles (EVs) circulating in the bloodstream. Eggs obtained from Tg(kdrl:mCherry-F) fish were transfected with DNA plasmids by microinjection into the yolk syncytial later (YSL) that is formed at 3-4 hpf. The caudal vein tissue of the transfected embryos at 3 dpf was imaged every minute for 30 min. YSL EVs in yellow, endothelial cells in grey. (Movie: Yuya Hayashi)

Pro-inflammatory activation of macrophages visualized in real-time.Tg(tnfa:EGFP-F); Tg(mpeg1:mCherry) embryos at 3 dpf were injected with Pacific Blue-labelled 70 nm SiO₂ nanoparticles (10 ng) with protein corona pre-formed of FBS. The caudal vein tissue of the embryos was imaged every 20 min for 1-12 hpi. Left panel shows Cy5-labelled protein coronas (cyan), macrophages (grey), and transcriptional activation of tumour necrosis factor-alpha (yellow). Right panel shows only the latter two after applying a mask created with the macrophage reporter signals. (Movie: Yuya Hayashi. Adapted from Mohammad-Beigi et al. (2020) ACS Nano. Copyright 2020 American Chemical Society)

Visualizing the interaction of macrophages with nanoparticles in the blood vessels. Macrophages (magenta) with internalized nanoparticles (cyan) crawling along the inner side of blood vessels (yellow). Tg(fli1a:EGFP); Tg(mpeg1:mCherry) embryos at 3 dpf were injected with Pacific Blue-labelled 70 nm SiO₂ nanoparticles (2 ng). Time-lapse imaging was performed at the intervals of every 16 s for 15 min at 1-4 hpi. (Reprinted from Hayashi et al. (2020) ACS Nano. Copyright 2020 American Chemical Society)