A team of scientists at Stanford University has genetically reprogrammed neurons that could enhance the function of electrical implants used in a variety of clinical scenarios, such as in treating Parkinson’s disease and epilepsy or connecting nerve cells to prosthetics.
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Genetically modifying neurons
After many years of research, scientists have successfully demonstrated that they have a method of modifying neurons which would allow them to build artificial structures.
The basis of the method relies on genetically modifying specific types of nerve cells, causing them to produce conductive or insulating polymers on their surfaces, having the impact of changing their electrical properties. The innovation could be used to improve connections with implants, such as those used to control next-generation prosthetics, connecting them with the movement management areas of the brain so they can be controlled just as a natural limb would be.
The team achieved this by combining polymer chemistry with engineered-enzyme targeting. The brain’s living neurons were instructed to synthesize specific, conductive or insulating polymers at the cell’s membrane.
It is predicted that this will allow specific groups of cells to be controlled electrically, which could be used to innovate enhanced treatments for diseases such as epilepsy or neurological disorders, as well as in creating enhanced prosthetics, as discussed above.
Producing enzymes to create polymers
Currently, neural implants are inserted into the brain, into tissue that contains neurons, to interact with them electrically. While work into developing these implants has gained much traction due to their huge untapped potential, they are still limited by the fact that there is still no way of controlling how the specific types of neurons behave.
To address this, the team at Stanford genetically modified specific cell types. These modifications led to the cells producing enzymes on their membranes that create chains of monomers, known as polymers. These chains can either work as conductors or insulators.
The effectiveness of the team’s method was first demonstrated in the lab with animal cells, and then with human ones. Once they’d confirmed that the method was successful in the dish they moved on to testing it on living brain structures, such as those in living nematode worms. The team soaked the worms in the monomers that the enzymes would join together to construct the polymers.
As a result, it was observed that the polymer has successfully coated the targeted nerve cells, altering the behavior of the cells in the way researchers had predicted. For example, in targeting the neurons that govern movement, the worms became less likely to make certain movements depending on the polymer, such as move forward to take sharp turns.
Analyses of electrophysiology and behavior determined that genetically targeted assembly of functional polymers both preserved neuronal viability and remodeled the properties of the cell’s membrane. This has resulted in cell type-specific behaviors being modified in freely moving animals.
At this moment, the researchers involved in the study aren’t sure what causes the modifications to generate these effects. In addition, they still need to develop a method to connect and interact with these modified neurons. However, the study acts as a proof of principle, which will be built on by future studies.
Scientists will be exploring how this innovation could be used to investigate and gain insights into a number of diseases, such as multiple sclerosis, epilepsy, and autism, all of which have strong neuropathological origins. This would give researchers a chance to develop therapies to modify and improve these conditions.
Right now, researchers are focusing on exploring how their cell-targeted technology could be adapted to create functional materials. With this work, the door has been opened to a wide range of new possibilities that will benefit from this interface of chemistry and biology.
Liu, J. et al. (2020). Genetically targeted chemical assembly of functional materials in living cells, tissues, and animals. Science. DOI: 10.1126/science.aay4866