(A) Schematic representation of experimental groups. Four combinations of OS cells and TAMs were cultured on five sets of electrospun scaffolds ranging from 100% PCL with the highest stiffness to 100% gelatin with the lowest stiffness. (B) Representative confocal microscopy images demonstrating the morphology of MG-63 osteosarcoma and THP-1 macrophage cells on electrospun PCL scaffolds after 24 h culture or co-culture. Cells were co-stained for CD68 (red), Sox2 (cyan), phalloidin (actin, green), and Hoechst (nuclei, blue). Focused projection images of 20 μm z-stacks. Scale = 25 μm.