Scaffold free fabrication of linear multicellular assemblies by dielectrophoretic hydrogel trapping technique

We have designed a scaffold-free cell assembly method which can produce linear structures of individual living cells without using templates. The method involves dielectrophoretic assembly of cells suspended in a solution of a gelling agent above the gelling temperature. After the cell assembly in string-like structures was achieved with the AC electric field still applied, we gelled the solution by cooling it below its gelling point. The hydrogel entraps the assembled cell structure, preventing its disassembly and allowing further analysis without the presence of the external electric field. We pre-functionalised the cells with polyelectrolytes before the dielectrophoretic assembly which allowed us to line them up in multicellular strings and bind them together with oppositely charged polyelectrolyte after the gel formation. Finally, by dissolving the hydrogel, we released the linear chains of living cells which were collected and studied by optical and fluorescence microscopy. Cell viability tests with fluorescein diacetate confirmed that the cells in the formed worm-like structures remain viable after the cell assembly procedure. The linear cell aggregates are stable without the electric field and can be further cultured or treated with additional polyelectrolytes which make the method attractive for tissue engineering. We envisage that this technique could find possible applications for assembly of neuron cells in linear structures and more complex cell networks.