Insert-based microfluidics for 3D cell culture with analysis.

We present an insert-based approach to fabricate scalable and multiplexable microfluidic devices for 3D cell culture and integration with downstream detection modules. Laser-cut inserts with a layer of electrospun fibers are used as a scaffold for 3D cell culture, with the inserts being easily assembled in a 3D-printed fluidic device for flow-based studies. With this approach, the number and types of cells (on the inserts) in one fluidic device can be customized. Moreover, after an investigation (i.e., stimulation) under flowing conditions, the cell-laden inserts can be removed easily for subsequent studies including imaging and cell lysis. In this paper, we first discuss the fabrication of the device and characterization of the fibrous inserts. Two device designs containing two (channel width = 260 μm) and four (channel width = 180 μm) inserts, respectively, were used for different experiments in this study. Cell adhesion on the inserts with flowing media through the device was tested by culturing endothelial cells. Macrophages were cultured and stimulated under different conditions, the results of which indicate that the fibrous scaffolds under flow conditions result in dramatic effects on the amount and kinetics of TNF-α production (after LPS stimulation). Finally, we show that the cell module can be integrated with a downstream absorbance detection scheme. Overall, this technology represents a new and versatile way to culture cells in a more in vivo fashion for in vitro studies with online detection modules. Graphical abstract This paper describes an insert-based microfluidic device for 3D cell culture that can be easily scaled, multiplexed, and integrated with downstream analytical modules.