Fig. 1

Design of the microfluidic device and flow field rate simulation. a Components of the microfluidic device assemblage for cell culture and induction of hepatic differentiation of MSCs. b Schematic illustration of the cell culture procedure to induce hepatic differentiation using the microfluidic device. Cells were initially seeded unto the cell-loading device and allowed to adhere onto the substrate (a). After 24 hours, the cell loading device was aseptically removed and the substrate was assembled with the other microfluidic components (b), cultured in hepatic induction medium and monitored by time-lapse microscopy (c). c Simulation of medium diffusion in a pre-established flow field. The flow field (green) shows a uniform flow profile in the culture chamber of the device. d Actual flow field area subjected to two flow rates (100 and 500 μl/hour) during culture medium replacement. The medium flow rate of 100 μl/hour from left to right starts upon injection of the culture medium. Addition replacement at t = 0 minutes (a), replacement progression at t = 10 minutes (b) and t = 20 minutes (c), and complete replacement at t = 30 minutes. The flow rate of 500 μl/hour (lower panel) shows start of the replacement, t = 0 minutes (e). Replacement progression at t = 2 minutes (f) and t  = 4 minutes (g). Complete replacement at t = 6 minutes (h). e Schematic representation in lateral view of air bubble removal by negative pressure during injection of culture medium into the cell culture chamber. PDMS polydimethylsiloxane, PMMA polymethyl methacrylate