2D and 3D thermally bioprinted human MCF-7 breast cancer cells: A promising model for drug discovery.
2605 Background: Breast cancer (BC) is the second leading cause of cancer death following lung cancer. Bioprinting, the use of computer aided process to print biological living and non-living material to create patterns in 2D or 3D structures, is a novel technique that has been proposed to be used to develop tissue engineered solutions for a wide array of clinical applications, e.g., skin grafting. We investigate here if bioprinted breast cancer cells show some of the hallmarks of cancer tissues, and thus may represent good in vitro models for drug discovery. Methods: For this study, MCF-7 BC cells were cultured, stained, counted and turned into a bioink solution by suspending in phosphate buffered saline solution. The cells were bioprinted over a 96-well plate and pre-incubated for 18 hours in DMEM and RPMI media with 10% Fetal Bovine Serum and Charcoal Stripped Serum, respectively. After 18 hours of incubation the media was supplemented with Tamoxifen at 5µM, 10µM, 50µM, 90µM and 110µM concentrations. Cytotoxicity was measured 24 hours post-treatment using a differential nuclear staining assay and an INCell 2000 bioimager system. Results: Bioprinted cells exposed to high concentrations of Tamoxifen (90 µM and 110µM) exhibited a viability of 8.2% and 10.8%, respectively. Whereas viability of manually seeded cells at those concentrations was 0.11% and 0.05%. Viability of negative and positive controls was at 7.6% and 97.0% for the bioprinted samples and for the normally seeded cells was 4.9% and 98.8% respectively. Conclusions: In our study, we have established a novel 2D/3D breast tumor model applying bioprinting technology for drug discovery. The higher cell viability of MCF-7’s at high concentrations of Tamoxifen could be attributed to the hormesis effect and activation of chaperone proteins, e.g., HSP70 and HSP90, possibly caused by bioprinting. We hypothesize that bioprinted MCF-7 cells also show increased levels of chaperone proteins, which may in a way mimic their in vivo behavior. In this novel in vitro 2D/3D model, the bioprinted cells show a more biological relevant behavior than normally cultured cells. Insights into the cell behavior after bioprinting may elucidate how to build improved in vitro models for BC research.