On-chip Formation and Fusion of Spheroids by Label-free Magnetic Cell Manipulation

ABSTRUCT This paper demonstrates a method to form and fuse spheroids on a microfluidic chip without cell labeling nor specific pattern of a microchannel. Label-free magnetic cell manipulation became possible by adding a paramagnetic salt into culturing medium to enhance the diamagnetic property of the cells. Cells in the paramagnetic medium were aggregated ultrarapidly within a microchannel by applying a magnetic field. The spheroids were manipulated by changing the magnetic field. We also succeeded in fusing two different spheroids into a Janus spheroid on the same chip.