Electrically controlling cell adhesion, growth and migration.

We have developed a neurochip to control the adhesion and outgrowth of individual neurons by electrochemical removal of protein repellent molecules from transparent electrodes. The neurochip architecture is based on three parallel indium-tin-oxide (ITO) electrodes on a SiO(2) substrate and a photoresist structure forming a landing spot for the neuron soma and two lateral outgrowth pathways for the neurites. The whole surface was turned protein and cell repellent with poly(ethylene glycol) grafted-poly(L-lysine) (PLL-g-PEG) before enabling neuron soma adhesion by selective PLL-g-PEG removal. After the neuron has settled down a potential was applied to the pathway electrodes to permit the neurite outgrowth along pathways formed by the SU8 structure. We also show the possibility to control cell migration by small pulsed currents. Myoblasts were therefore seeded on a chemical pattern of cell adhesive PLL and cell resistant PLL-g-PEG. The PLL-g-PEG was then removed electrochemically from the electrodes to permit migration onto the cell free electrodes. Electrodes without applied current were confluently overgrown within 24 h but a small pulsed current was able to inhibit cell growth on the bare ITO electrode for more than 72 h. With both techniques, cell adhesion, growth and migration can be controlled dynamically after the cells started to grow on the substrate. This opens new possibilities: we believe the key to control the development of topologically controlled neuron networks or more complex co-cultures is the combination of passive surface modifications and active control over the surface properties at any time of the experiment.