Spheroid array formation by non-label cell manipulation using magneto-Archimedes effect

This paper demonstrates spheroid array formation by a label-free three-dimensional (3D) cell assembly method which is based on the magneto-Archimedes effect. A paramagnetic salt (Gd-DOTA) is added to the culturing medium to enhance the diamagnetic property of the cells, by which label-free magnetic manipulation becomes possible. In this study, a chamber including cells suspended in the paramagnetic medium was placed on a magnet array, and spots with low (that is, almost zero) magnetic flux densities were formed on the array with the magnet array, on which the cells aggregated. These cell aggregates became spheroids after one day of culture. The result suggests that this 3D cell assembly method is a promising approach to construct micro 3D tissues in a closed small space.