Fig. 4: Arp3 expression is increased in hippocampal neurons after U87-derived exosome treatment.

Representative confocal images of control (Ctr) and exosomes treated (Exo) hippocampal neuron cultures at 4 DIV (A) and 7-12 DIV (C) stained with antibodies for Arp3 (green channel) and DAPI for nuclei (blue channel). Scale bar: 20 µm. Arp3 staining quantification at 4 DIV (B) and 7–12 DIV (D) showing a statistically significant increase in both groups. Unpaired Student’s t-test, **p < 0.01, n = 3 independent cell preparations per group; quantification of 27 fields per group from three coverslips, was performed. Graphs show average ± SEM. Representative western blot images from the same experimental conditions are shown on the right; here, GAPDH is used to verify equal loading. E Comparison of synaptic currents at DIV 4. Left: overlay of peak currents distribution from several voltage-clamp recordings. Black: control neurons (n = 4); blue: U87 exosome-treated neurons (n = 6). Exosome treatment increased the number of synaptic events between 1 and 6 pA, suggesting higher connectivity. F average peak currents distribution from the recordings shown in (E). Kolmogorov–Smirnov test, **p < 0.01. Representative voltage-clamp traces at −70 mV in control and U87 exosome-treated hippocampal neurons are shown at the bottom.