(69e) Microfluidic Co-Culture of Triple Negative Breast Cancer Cells and Adipose Stem Cells

Breast cancer is currently the second leading cause of cancer deaths in women in the United States. In the tumor microenvironment, adipose stem cells (ASCs) growing in close proximity to breast cancer cells can induce phenotypic and genotypic changes in both cell types, which can increase breast tissue density and result in poorer patient prognosis. ASCs also increase the metastatic potential in a breast tumor by differentiating cells within the tumor into several types of stromal cells, such as adipocytes and fibroblasts. Current methods to co-culture two different types of cells use transwell chambers or conditioned media which both are limited to end point assessment and lack dynamic control. In this study, a microfluidic device was developed address this limitation and investigate this phenomena by simultaneously co-culturing both MDA-MB-231 cells and ASCs. The microfluidic device consists of a top PDMS fluidic layer on top of a bottom agarose diffusive layer to facilitate the crosstalk between the two cell types. The device contains four fluidic channels imprinted into the top PDMS layer: two inner ‘flow-free’ channels to culture the 231 cells and ASCs and two outer ‘flow’ channels to supply the device with media. The two center channels were designed to be 200 µm apart which allows for facile diffusion of external chemical cues generated by the two different cell types as confirmed by COMSOL simulation. Cellular attachment to the basement agarose layer was facilitated by pre-treating the agarose with poly-D-lysine. A strength of the microfluidic approach is the ability to directly visualize cell growth and morphology during experimentation. Additionally, the device can be easily dissembled to allow for terminal analysis on the cells including immunostaining for viability and proliferation fluorescence microscopy. Device performance was confirmed by five-day culturing of 231 cells and ASCs separately followed by quantification of cellular viability, growth, and proliferation using cell counts and fluorescent stains (Calcein-AM, DAPI, KI-67). Observed growth rate and morphology of MDA-MB-231 cells and ASCs in the microfluidic device was analogous to growth in a culture flask. A five-day co-culture experiment found an increased growth rate and enhanced elongation and polarization of the 231 cells in the presence of the ASCs. Finally, the device was used to assess how chemotherapeutic drugs targeting MDA-MB-231 cells affected cell proliferation, morphology, and protein expression in both cell lines.