Mesenchymal stem cells and glioma cells form a structural as well as a functional syncytium in vitro

► Cx43 is the predominantly expressed gap junction protein in MSC and U87 cells. ► mRNA expression of Cx43 changes significantly in co-cultured glioma and MSC cells. ► Co-culture of glioma cells and MSC shows structural and functional syncytia formation. ► Co-culturing in mixed spheroids enhances migration of glioma cells and MSC. ► Inhibition of gap junctions reduces cell migration out of spheroids.