2.5 Cell culture conditions and tumor spheroid preparation
Human tumor cells were purchased from the American Type Culture Collection (ATCC). The human breast cancer cell lines MCF-7, MDA-MB-361, MDA-MB-231 and the human neuroblastoma SH-SY5Y cells were cultured as 2D monolayers in DMEM medium (4500 mg/L glucose) supplemented with 10% FBS, 100 U/mL penicillin and 100 μg/mL streptomycin at 37 °C in an atmosphere of 5% CO2.
The cells were trypsinized, counted and added to the A-C blend at a density of 2.5x104 cells/mL in complete growth medium. The cell suspension containing agarose and collagen was let to gel into the well plate. Then, 1 mL of DMEM was added over the cell-embedded hydrogels prior to transfer the plate into the incubator. The medium was changed every 4 days.