Exposure of MDA-MB-231 cells to MSC CM did not significantly affect the cytotoxic effect of Dox. MDA-MB-231 cells were incubated with 0–500 nM of Dox and both conditioned media, CM2D or CM3D, and cytotoxicity was evaluated by MTS reduction assay. Cell viability is expressed in percentage (mean ± SD, n = 3–6) to non-treated MDA-MB-231 cells (control). Grid line represents 100% cell viability (control). Statistical significance is expressed relative to control of non-treated cells, i.e., 100% viability as ##
p < 0.01, ####
p < 0.0001. CM2D, conditioned medium derived from 2D cultures; CM3D, conditioned medium derived from 3D cultures; Dox, doxorubicin.