Magnetogenetics: A New Technique to Control the Inner Workings of Human Cells and Build Neural Circuits

From ExtremeTech:

In the brain, the complex circuits behind our cognition largely construct themselves. In a dish or on a chip however, the normal meaningful cues are missing, and any attempts to grow predefined circuits from neurons have largely met with failure. A new technique, dubbed magnetogenetics, has now provided a way to create these neural circuits by combining magnetic manipulation with the cell's own machinery for stabilizing new growth and extensions.

The technique works by making use of the cell's ability to target a protein, known as Rac-GTPase, which promotes the formation and stabilization of new branches. The researchers used 500nm (0.0005mm) magnetic beads that have been modified so they can hook up to these protein machines soon after they come off the presses. They can then be magnetically acquired, and then moved to the desired locations using a precisely controlled force. In order to see what they are doing, they also attached fluorescent beacons to the beads.

Other researchers had previously tried mechanically pulling on the cells with microactuators, and while impressive growth could be obtained, fine control was impossible. Other techniques using laser tweezers to pull on subcellular transparent beads, or even the cell directly also had some successes, but the level of light power necessary to do this is typically damaging to the cells. (See: Manipulating nanoparticles with an electron tractor beam.) To grow neurons on semiconductors, adhesion molecules have typically been pre-patterned along traces for the neurons to follow. When these molecules invariably degraded over time, the neuron was left without any natural supporting structure. By using a machine that nucleates the cellular endoskeleton directly, new processes can be drawn out in a more natural way that the cell can adapt to.

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