Artificial Neurons for replacing damaged nerve cells
Dr Agneta Richter-Dahlfors
Opening a score of exciting possibilities, Swedish researchers have built the world’s first artificial neuron to mimic organic brain cell function. Importantly, the artificial neuron can translate chemical signals into electrical impulses, opening the potential for communication with other human cells. This remarkable research offers interesting potential for future treatments to help paralyzed and Parkinson’s Disease patients, among others.
Doctor Agneta Richter-Dahlfors and her team at the Karolinska Institutet’s Department of Neuroscience in Sweden have created artificial neurons by connecting enzyme-based biosensors to organic electronic ion pumps. With an infectious diseases background, Richter-Dahlfors explains that initially the team developed the device to induce calcium fluxes with specific frequencies as this happens within the host during infection. They tested various chemicals for transportation. She says, "We tried acetylcholine just for fun because it always has a positive charge and it worked like boom! It super efficiently transported."
Previous brain cell stimulation research had been limited by only being able to stimulate the cells by electrical impulses, while in the human body they are stimulated by chemical signals, enabling them to communicate with other neurons. "At the end of the axon there is a synapsis and it’s not the electrical signal that moves across to the next cell, it’s the chemical substances. The electrical signal along the axon is translated to chemical output. You have chemical input translated to an electronic signal that is translated to a chemical output", explains Richter-Dahlfors.
The team’s artificial neuron mimics the body’s organic electronic pumps function and have demonstrated that not only can it communicate effectively with organic brain cells, but communication can be over long distances. This means that in theory the artificial neurons eventually could be implanted in humans to bypass or even replace damaged nerve cells. Made of conductive polymers, they function like organic human neurons. Electronic control of delivery also means that there is the potential to send signals anywhere in the body through wireless communication. She notes that because there is an electronic on/off control, only the right number of molecules that are required would be delivered each time. However, more research is needed to learn what number of molecules is needed in each situation.
WE TRIED ACETYLCHOLINE JUST FOR FUN BECAUSE IT ALWAYS HAS A POSITIVE CHARGE AND IT WORKED LIKE BOOM! IT SUPER EFFICIENTLY TRANSPORTEDDoctor Agneta Richter-Dahlfors
With both electronic and medical innovations accelerating in parallel, Richter-Dahlfors predicts the research could merge into very exciting applications. She suggests, "You can think of having a sensory function in one place, say the brain, and your delivery device at a muscle some distance away, say a muscle in the leg." This offers clear potential for paralyzed patients, including those with spinal cord injuries, as well as patients with other muscle control disorders including Parkinson’s Disease. Auto-regulated sensing and delivery or via a remote control device could facilitate rehabilitation and long-term treatments for many patients suffering from neurological disorders.
Another area that offers interesting potential for the artificial neurons is ph regulation by proton transport. Richter-Dahlfors also highlights regulation of micro environments, such as infection site research in vitro. "We had a paper where we used these conducting polymers to modulate the local micro environment when we used a sensor for the C-reactive protein for effective binding to the C-reactive protein receptor to see what conditions you need to get that binding. It could show what is happening at the local tissue site during infection. There are very few methods today where you can make these dynamic studies," she says.
Finger-tip sized, dimension is one challenge for artificial neuron development, but the team is working on miniaturization. Richter-Dahlfors explains, "If you think of the deep brain stimulation electrodes that exist, that’s the size it needs to be at a later stage when clinicians begin to work on this. The miniaturization will depend on where it is delivered."
Joakim Isaksson, Peter Kjäll, David Nilsson, Nathaniel Robinson, Magnus Berggren, Agneta Richter-Dahlfors, "Electronic control of Ca2+ signalling in neuronal cells using an organic electronic ion pump" In Nature Materials (2007) Available here: http://www.nature.com/nmat/journal/v6/n9/abs/nmat1963.html
Daniel T. Simon, Sindhulakshmi Kurup, Karin C. Larsson, Ryusuke Hori, Klas Tybrandt, Michel Goiny, Edwin W. H. Jager, Magnus Berggren, Barbara Canlon, Agneta Richter-Dahlfors, "Organic electronics for precise delivery of neurotransmitters to modulate mammalian sensory function" In Nature Materials (2009) Available here: http://www.nature.com/nmat/journal/v8/n9/abs/nmat2494.html
Daniel T. Simon, Karin C. Larsson, David Nilsson, Gustav Burström, Dagmar Galter, Magnus Berggren, Agneta Richter-Dahlfors, "An organic electronic biomimetic neuron enables auto-regulated neuromodulation" In Biosensors and Bioelectronics (2015) Available here: http://www.sciencedirect.com/science/article/pii/S0956566315300610
S. Löffler, A. Richter-Dahlfors, "Phase angle spectroscopy on transparent conducting polymer electrodes for real-time measurement of epithelial barrier integrity" In J. Mater. Chem. B (2015) Available here: http://pubs.rsc.org/is/content/articlehtml/2015/tb/c5tb00381d
T. Goda, P. Kjall, K. Ishihara, A. Richter-Dahlfors, Y Miyahara, "Biomimetic interfaces reveal activation dynamics of C-reactive protein in local microenvironments" In Advanced Healthcare Materials (2014) Available here: http://www.ncbi.nlm.nih.gov/pubmed/24700816