Figure 5.

DSPC–LNP biodistribution and mRNA expression within, four-day old, wild-type (AB/TL) embryonic zebrafish, with and without preincubation with human apoE. a) Schematic showing the site of DSPC–LNP injection (i.v.) within embryonic zebrafish (4 dpf). DSPC–LNPs (10 × 10⁻³ m) contained DiD (0.1 mol%) as fluorescent lipid probe and unlabeled, eGFP mRNA (capped) payload after 1 h incubation with/without human apoE. Injection and imaging timeframe. Injection volume: 1 nL. PHS: primary head sinus. b,c) Whole embryo (10× magnification) and tissue level (liver region, 40× magnification) views of DSPC–LNP biodistribution at 1.5 hpi. Injected dose: ≈10 × 10⁻³ m lipid, ≈0.2 mg kg⁻¹ mRNA. LNPs were mostly freely circulating with no significant accumulation in the liver at 1.5 hpi. Intense fluorescent punctae within the liver region are likely due to macrophage uptake. d,e) Whole embryo (10× magnification) and tissue level (liver region, 40× magnification) views of eGFP expression at 24 hpi. f,g) Whole embryo (10× magnification) and tissue level (liver region, 40× magnification) views of DSPC–LNP biodistribution, following preincubation (1 h) with apoE (5 mg μL⁻¹; 1:1 v/v), at 1.5 hpi. Injected dose: ≈10 × 10⁻³ m lipid, ≈0.2 mg kg⁻¹ mRNA. LNPs were mostly freely circulating with no significant accumulation in the liver observed at 1.5 hpi. Intense fluorescent punctae within the liver region are likely due to macrophage LNP uptake. h,i) Whole embryo (10× magnification) and tissue level (liver region, 40× magnification) views of eGFP expression at 24 hpi. In this case, a qualitative increase in liver-specific eGFP expression was observed. Scale bars: 200 μm (whole embryo) and 50 μm (tissue level).