Figure 2

Characterization of tumor spheroids generation. (A) Micrographs of HT-1080, MDA-MB-231, and MCF-7 cell spheroids with different cell concentrations after cultured in 2 days. All spheroids were cultured in a 30 µL hanging drop. (B) The diameter of HT-1080, MDA-MB-231, and MCF-7 cell spheroids over two days culture began with a different number of seeding cells. n ≥ 9 for each cell line. (C) The size distribution of MCF-7 spheroids cultured on single 3D-phd for two days. The MCF-7 cells were loaded at a density of 5 × 10⁴ cells mL⁻¹, and the medium was changed at 24 h after cell seeding. The average size of spheroids on this single device was 205 ± 20 µm (n = 96). (D) Series of confocal images of live/dead double-stained cell spheroids over 20 days. Scale bar is 100 µm. (E) Histogram analysis of cell viability and spheroid size changing. MCF-7 spheroids with 1500 cells/hanging drop were investigated over six days. n ≥ 5 for each bar. (F) Gene expression comparison between the 3D spheroid and 2D monolayer of MCF-7 cells. Relative expression (−∆∆Ct) of 11 genes has been profiled, and GAPDH was served as an internal reference gene. n = 6. Red and blue histograms indicate up- and down-regulation, respectively. Fold change (2^-∆∆Ct) > 2 was chosen as a criterion for a significant difference.