Nerve Cells
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Korean researchers have grown simple networks of nerve cells that could pave the way for a better model to test drugs, study the physiological roots of memory and help regenerate nerves in injured patients.

The team found that they could grow neurons in several shapes, including stars and squares. But triangles proved to be the most effective shape for encouraging the ends of the nerves, the axons, to grow, the scientists said in a study published on Friday in the Journal of Neural Engineering.

Co-author Yoonkey Nam said in a statement Friday that the motivation for the study was to know if we can design a neural tissue model that biologically mimics some neural circuits in our brain.

Neurons transmit electrical signals to each other through their axons, the tail-like structures that are the telegraph wires of the nervous system. When nerves grow, the axons seek other nerves by honing in on chemical signals.

Researchers in the current study attempted to recreate this natural process by positioning neurons taken from rats in differently shaped arrays on a glass surface. Each array was about one centimeter square.

Based on our results, we are suggesting a new design principle for guiding axons in a dish, Nam says. We can control the axonal growth in a certain direction by putting a sharp triangle pointing to a certain direction.

Nam and his colleague Min Jee Jang think that their model of shapes on a glass plate could be integrated into tissue scaffolds in order to help regenerate nerves in certain situations, like in spinal cord injury patients.

Growing nerves in a dish has already proven to be a powerful tool in investigating mental illness.

In 2011, a group of researchers published a paper in Nature describing how they transformed skin cells donated by schizophrenia patients into nerve cells by reprogramming them to become undifferentiated stem cells, then coaxed them to form neurons.

They found that the neurons from the patients didn't have as many interconnections as healthy neurons, and that various antipsychotic drugs seemed to increase the number of neuronal connections.

But growing nerves isn't necessarily a magic key to unlocking the brain's secrets. Cardiff University researcher Michael Owen cautioned against drawing the simple conclusion that differences in neurons are the root cause of schizophrenia in an interview with Nature News, and McLean Hospital stem cell scientist Kwang-Soo Kim said the differences the researchers found could be from the process of reprogramming the cells, not innate differences in the nerves of mentally ill people.

SOURCE: Jang et al. Geometric effect of cell adhesive polygonal micropatterns on neuritogenesis and axon guidance. Journal of Neural Engineering 9: 046019.