Fabrication of three-dimensional islet models by the geometry-controlled hanging-drop method

The hanging-drop method has been widely used to fabricate three-dimensional (3D) in vitro tissue models due to its advantages such as being easy to perform, inexpensive, and permitting precise control of cell spheroid formation. The geometry of hanging drop may play a critical role on the formation of cell spheroids, which, however, has not been explored. In this study, we developed a modified hanging-drop platform that enables the production of cell spheroids in a high-throughput manner by controlling hanging drop geometry with a defined spreading ring. The surface tension force is proportional to the spreading ring and the gravitational force is determined by droplet volume, and the geometry can be determined by the balance between surface tension and gravity. β-TC-6 cell spheroids with optimized diameters were fabricated as 3D in vitro islet models. The models showed morphology similar to primary islets and had functionality that more closely resembled primary islets than two-dimensional cell culture. The developed platform holds great potential for engineering well-controlled in vitro tissue models for various applications such as physiological and pathological studies, drug screening, as well as transplantation for treatment purpose.