Cell patterning using magnetite nanoparticles and magnetic force.

Technologies for fabricating functional tissue architectures by patterning cells precisely are highly desirable for tissue engineering. Although several cell patterning methods such as microcontact printing and lithography have been developed, these methods require specialized surfaces to be used as substrates, the fabrication of which is time consuming. In the present study, we demonstrated a simple and rapid cell patterning technique, using magnetite nanoparticles and magnetic force, which enables us to allocate cells on arbitrary surfaces. Magnetite cationic liposomes (MCLs) developed in our previous study were used to magnetically label the target cells. When steel plates placed on a magnet were positioned under a cell culture surface, the magnetically labeled cells lined on the surface where the steel plate was positioned. Patterned lines of single cells were achieved by adjusting the number of cells seeded, and complex cell patterns (curved, parallel, or crossing patterns) were successfully fabricated. Since cell patterning using magnetic force may not limit the property of culture surfaces, human umbilical vein endothelial cells (HUVECs) were patterned on Matrigel, thereby forming patterned capillaries. These results suggest that the novel cell patterning methodology, which uses MCLs, is a promising approach for tissue engineering and studying cell-cell interactions in vitro.