Open-access Microfluidic Tissue Array System For Screening Of Anti-Cancer Drug Combinations

Objective: To develop a microfluidic system for anti-cancer drug combination screening.Methods: We designed and fabricated a microfluidic chip in which a nanoporous membrane is sandwiched by an open-access media reservoir layer and a cell culture chamber array layer.The microfluidic approach takes advantage of the characteristics of the nanoporous membrane: on one side,this membrane permits the flow of air but not liquid,thus acting as a flow-stop valve to enable automatic cell distribution;on the other side,it allows diffusion-based media exchange and thus,mimics the endothelial layer.In synergy with a liquid transferring platform,the open-access microfluidic system enables complex multi-step operations involving long-term cell culture,medium exchange,multi-step drug treatment,and cell viability testing.By using the microfluidic protocol,tissue arrays were constructed from breast cancer cells followed by schedule-dependent drug testing.Robustness of the microfluidic system was demonstrated by implementing the screening of orthogonal anti-cancer drug combinations,and the optimal drug combination was selected depending on the outcome of cell viability test.Results:We fabricated a microfluidic chip with 10×10 cell culture arrays and achieved a serial of operations on the microchip,including automatic cell distribution,long-term cell culture,medium exchange,multistep drug treatment and cell viability testing.Breast cancer cells seeded on the microchip continued to proliferate and formed a tissue similar structure on the third day,and cell viabilities were maintained higher than 90%.Immunofluorescence analysis showed the expressions of a serial of markers in cells cultured in microchip 3D environment were similar to those grows in vivo.Cells cultured under different environments differed in cellular responses to anti-cancer agents.The IC50 values of MCF-7 cells and LO2 cells increased in the order of 2D→3D→Chip 3D.Following the outcome of a 3-level-3-factor orthogonal experiment,an optimal drug combination was selected to achieve maximum tumor killing effect and minimum unwanted toxicity.Conclusion:An open-access microfluidic tissue array system was developed for anti-cancer drug combination screening.Experiment results demonstrated that the microfluidic system promised tissue-based drug screening with complex and multistep operation procedures.The microfluidic protocol presented herein is flexible and easy-to-use,thus providing an ideal tool for drug combination screening.