Figure 3

Endocytosis of nucleic acids impairs inter-neuronal network communication. (a–c) After network formation, primary cortical neurons were analyzed for functional and synchronized Ca²⁺ signaling (left = all identified cells, right = synchronized cells in green and inactive cells in red) in the absence and presence of endosome inhibitor β-MCD. Inhibitor was added to the culture medium two hours before cells were transfected with GFP-mRNA by endosomal-independent ((b), fusion) or endosomal-dependent ((c), lipofection) transfer mechanisms and compared to the untransfected control (a). Statistical evaluation of all experiments including s.d. (d) Here, +B: addition of endosomal inhibitor β-MCD. eGFP-mRNA was used in a concentration of 4 µg/mL for fusion and 2 µg/mL for lipofection. In all cases, a total of 1 µg was transferred per substrate. Scale bar = 200 µm. n = three independent experiments with at least 9 independently formed neuronal networks. p-values: not significant (n.s.): p > 0.05, *: p ≤ 0.05, ***: p ≤ 0.001.