To determine whether miR-145-5p was transferred from endothelial to cancer cells, we transfected HMEC with a miR-145-5p mimic (30 nM) before culturing them with DiL-C18-labelled U87 (ratio 1:1) for 12 hours. The two cell types were subsequently sorted by flow cytometry and miR145-5p expression was measured in each population. Both HMEC and U87 expressed high levels of miR-145-5p (Figure 2A). To evaluate the contribution of cell-to-cell contact in this transfer, we cultured U87 with miR-145-5p-transfected HMEC in transwell plates to prevent any cell-cell contact. In these non-contact conditions, we failed to detect any increase in miR-145-5p expression level in U87 (Figure 2B). These results indicate that U87 do not ingest extracellular miR-145-5p, either free or incorporated into soluble exosomes .