Figure 4

Endosome-independent transfer allows efficient transfection rates with low cytokine response in vivo. (a) The brain of adult zebrafish was injected with GFP-mRNA containing fusogenic liposomes (top) or dependent on endosomal uptake (lipofection, bottom). Injection into the ventricle is indicated by a red arrow, upper right of the image shows ventricular zone of zebrafish brain. A total of 24 h after nucleic acid transfer, whole brains were isolated and brain sections were stained for GFP (green) and nuclei (blue). Co-stained nuclei were counted as transfected cells and are given as percentage of all cells. The whole RNA of identically treated brains was isolated 24 h after nucleic acid transfer and tested for IL-6 and TNF-α expression (b). LPS was used as positive control, PBS as negative control. eGFP-mRNA was used in a concentration of 0.3 ng/µL (corresponds to 1.5 ng per injection). Scale bar = 200 µm. Each condition was analyzed on at least 5 independent injections. p-values: not significant (n.s.): p > 0.05, *: p ≤ 0.05, **: p ≤ 0.01, ***: p ≤ 0.001.