GJIC in BMSCs is enhanced with Cx43 overexpression. Images demonstrate the transfer of calcein in BMSCs (A), BMSC-Cx43 (B), BMSC-BMP7 (C), and mutant BMSC-Cx43Δ7 cells (D) after 5 h of exposure to donor cells. Arrows indicate donor cells (DiI, wide field inverted) overlaid in the images. The transfer fraction of calcein-AM was measured for cells cultured in monolayer and 3D (E). Cells overexpressing Cx43 had a significantly higher transfer fraction than non-Cx43-transduced cells. Transfer was significantly enhanced in 3D when cells overexpressed Cx43 relative to 2D. Cells that did not overexpress Cx43 showed significantly less dye transfer in the core of the scaffolds compared to the periphery, whereas no significant difference was evident in cells overexpressing Cx43 (F). Horizontal bars represent pairs that are significantly different; * indicates groups that are significantly greater than BMSCs; ** indicates groups that are significantly less.