3D lab-grown nerves match human sensory signal speeds

The electrodes are small, but the question is large: can a dish of human nerve cells reproduce the way a living nerve carries a signal? At Rice University and ETH Zurich, researchers grew human-derived sensory neurons in a soft hydrogel, added Schwann cells that build the protective myelin coating around nerve fibers, and recorded the networks in real time. The new platform produced signals at conduction velocities in the same range as human sensory nerves.

The system, called hydroMEA, brings three elements together: human-derived cells, a three-dimensional hydrogel and a high-density multielectrode array from Maxwell Biosystems. Microfluidic channels guide the cells as they grow, while the electrodes measure electrical activity. Unlike conventional tissue-culture plastic, the hydrogel is soft and water-rich, and its stiffness can be adjusted to more closely resemble nerve tissue.

The researchers kept the neurons alive for more than 100 days. Imaging confirmed that myelin had formed around the axons—the long fibers that carry nerve signals—and the electrical recordings supplied the crucial second test: signals traveled faster when neurons were grown with Schwann cells. The measurements came from the laboratory system described by the team in Advanced Healthcare Materials.

So what changes in practice? Scientists could use hydroMEA to watch nerve damage unfold without relying only on a static image. The team says it can expose the networks to trauma or toxins, track the resulting changes in electrical signaling, and test drugs or electrical stimulation aimed at preventing demyelination or encouraging remyelination.

The next experiment is not a clinical trial. Christina Tringides, an assistant professor of materials science and nanoengineering at Rice and the study's corresponding author, said the researchers want to deliberately damage myelin in the networks and then study recovery. The platform can also be adapted to model the brain, but whether results in this lab-grown system translate into living patients remains to be established.