Fig. 2: Glioma cells-derived exosomes disrupt network synchrony in mature (DIV 7–12) primary neuron cultures.

A–C Representative images of a Fluo-4 loaded DIV 10 control cortical neuron culture (A), of neurons co-cultured for 1 day with U87, mCherry expressing, glioma cells (B), and of neurons exposed for 1 day to U87-derived exosomes (C). ROIs indicate cells from which the representative Ca²⁺ traces are extracted. Scale bars, 50 µm. D Cross-correlation values of the various experimental groups. Data are shown as average ± standard error, significant differences were assessed with Wilcoxon–Mann–Whitney U test (to compare two groups) or Kruskal-Wallis test followed by Dunn’s multiple comparison post hoc test (to compare more than two groups); *p < 0.05; ***p < 0.001; ****p < 0.0001; n = 3 independent cell preparations, four coverslips for each preparation were analyzed and reported as superimposed individual points. E Representative raster plots of spike times, simultaneously detected at 120 spatial channels by MEAs: channels’ numbers are indicated on the y-axis. The spiking activity is displayed over a representative time window of 5 min, preceding the exposure to U87 exosomes (Ctr). At this stage of development (DIV 7–12), network bursts are normally observed. F Representative recording of the same neuronal culture in E after 24 h exosome exposure (Exo), showing a lower occurrence of network bursts. G Pearson correlation coefficients among spike times in different channels over 15 min recordings. The average correlation values across 10 channels were analyzed and their distributions were compared under control conditions and after exosomes, exposure using the Wilcoxon–Mann–Whitney U test; ***p < 0.001; n = 12, an average of 10 channels.