text: Above is a picture showing 3D cell culturing through magnetic levitation with the Bio-Assembler cell culturing system. The figure's letters refer to the following: 
  (A) A magnetic iron oxide nanoparticle assembly known as the "Nanoshuttle" is added and dispersed over cells, and the mixture is incubated. 
  (B) After incubation with Nanoshuttle, cells are detached and transferred to a petri dish. 
  (C) A magnetic drive is then placed on top of a petri dish top. 
  (D) The magnetic field causes cells to rise to the air–medium interface. 
  (E) Human umbilical vein endothelial cells (HUVEC) levitated for 60 minutes (left images) and 4 hours (right images) (Scale bar, 50 μm). 
  The onset of cell-cell interaction takes place as soon as cells levitate, and 3D structures start to form. At 1 hour, the cells are still relatively dispersed, but they are already showing some signs of stretching. Formation of 3D structures is visible after 4 hours of levitation (arrows).