Effect of chemotherapy drugs on cell viability in 2D and 3D cell systems: a) Morphology of treated cells grown in 2D as mono-culture (neuroblastoma tumor cells (SH-SY5Y) or MSC alone), and as cell co-culture (MSC and neuroblastoma cells together) with 5 μM of two chemotherapeutics, VP16 (Etoposide) or Cispl (Cisplatin), for 96 hours. Dashed circles highlight the residues of dead tumor cells. Stretched MSC can be observed below the debris of dead tumor cells. MSC isolated from two different donors were considered. b) Viability of treated cells grown in β-TCP scaffolds as cell mono- and co-culture compared to a conventional 2D cell growth. Treatments were done for 96 hours with 5 μM of VP16 (Etoposide) or Cispl (Cisplatin), and viability (1 equal to 100 %) normalized to the values of CCK-8 obtained before adding drugs. CTRL - DMSO treated control cells. ***p<0.001, ****p<0.0001, ns - not significant.