Fig. 2

Identification of scavenger endothelial cells (SECs) in zebrafish embryos. (a, b) Ex vivo imaging of adult Tie2:GFP transgenic mouse organs, 1 h after injection with DOPG liposomes. (a) Liposome accumulation is observed in liver, but not in the ear skin or heart muscle. (b) Within the liver, DOPG liposomes are observed as punctae within Tie2:GFP⁺ sinusoidal ECs (arrows) as well as sinusoid-associated cells which based on shape and position were identified as KCs (arrowheads). (c) Tissue level view of lithium carmine distribution in kdrl:GFP and mpeg:GFP transgenic zebrafish embryos, 1 h after injection. Lithium carmine (carminic acid) fluorescence co-localizes both with kdrl:GFP⁺ endothelial cells in the caudal vein and mpeg:GFP⁺ monocytes/macrophages (arrowheads) within the CHT. (d) Whole-embryo view of fluorescent oxLDL distribution in kdrl:GFP transgenic embryos, 1 h after injection. Accumulation of oxLDL is observed in the PHS, CCV, PCV, and CV. (e) Whole-embryo view of fluoHA distribution in kdrl:RFP transgenic embryos, 1 h after injection. Accumulation of fluoHA is observed in the PHS, CCV, PCV, and CV. (f) Tissue level view of fluoHA distribution in kdrl:RFP transgenic embryos, 1 h after injection at 102 hpf. FluoHA accumulation is observed in the entire caudal vein (CV), but only on the dorsal side of the PCV (dPCV, arrows). (g) Tissue level view of fluoHA in kdrl:RFP and mpeg:RFP transgenic embryos. Co-localization of RFP expression and fluoHA is observed only within kdrl:RFP endothelial cells, but not mpeg:RFP monocytes/macrophages. (h) Tissue level view of co-injected fluoHA and DOPG liposomes, 1 h after injection reveals co-localization in SECs. Monocytes/macrophages (arrowheads) take up DOPG but not fluoHA. (i) Ex vivo imaging of adult mouse liver, 1 h after injection with fluoHA and DOPG liposomes reveals widespread co-localization within sinusoidal ECs (arrows). KCs (arrowheads) take up DOPG liposomes only.