(49c) Intercellular Communication between Breast Cancer Cells and Adipose-Derived Stem Cells Using a Novel 3D-Printed Plate Insert Interfacing with an Agarose Hydrogel Layer

Intercellular communication is a physiological phenomenon crucial to development, disease progression, and wound healing in both multicellular and unicellular organisms. Cells secrete signaling molecules (e.g. growth factors, cytokines, hormones) into the extracellular space which are detected by neighboring cells to influence proliferation, migration, or apoptosis. Intercellular communication has been primarily investigated using the Transwell assay by co-culturing two different cell types in two separate chambers. This approach has several limitations including: (i) an inability to directly visualize the cells, (ii) the invasion of the cells in the top chamber into the polycarbonate membrane, and (iii) very low cellular yields for post-experimental analysis for PCR and western blot analysis. While microfluidic devices have garnered significant attention in recent years to overcome these limitations, they are still limited by total cellular yield which limits their use for common downstream analysis. To overcome these drawbacks, we developed a novel co-culture approach that utilizes a 3D-printed plate insert for a 10 cm petri dish that incorporates an agarose hydrogel layer to serve as a semi-permeable membrane to create two distinct culture chambers. The agarose hydrogel is coated with poly-D-lysine to facilitate cellular attachment, spreading, and growth of adherent cell lines in the top layer which physically separates the two culture regions, yet chemically connects them by allowing the mass transfer of biomolecules between the top and bottom layer. The approach design is user-friendly, inexpensive, and allows for dynamic and tunable co-culture conditions while preserving similar growth trends as compared to commonly used tissue culture plastic (TCP). Mass transfer experiment and COMSOL simulations confirm the rapid diffusion of biomolecules and oxygen across the hydrogel approaching a steady-state within ~12-18 hours. The plate insert approach allowed for the direct visualization of cell lines in both the top and bottom chambers facilitating the study of independent cell growth and morphology. A proof-of-concept study using the plate insert was performed to investigate intercellular communication between breast cancer cells and adipose-derived stem cells (ASCs). Recent studies have shown that ASCs play a critical role in promoting metastasis and drug resistance in breast cancer patients. The plate insert was used to study the interactions between two different breast cancer cell lines, MDA-MB-231 (triple-negative)and MCF7 (ER+), co-cultured with ASCs. Using this novel co-culture approach, enhanced cellular growth and overexpression of EMT-associated genes were identified in the MDA-MB-231 cell line when they were co-cultured with ASCs. Moreover, increased drug resistance in the MCF7 cell line in the presence of ASCs was observed through increased cell proliferation. The co-culture approach allowed for the independent harvesting of both cell lines in numbers sufficient for downstream PCR and Western Blot analysis to identify changes in the genotypic and phenotypic signature of cancer cells while this approach does not result in the infiltration of cells from the top layer to the bottom, preventing the cross-mixing of cells.