Synthetic Neurons

Synthetic neurons made of hydrogel could one day be used in sophisticated artificial tissues to repair organs such as the heart or the eyes. Hagan Bayley at the University of Oxford and his colleagues devised a synthetic material that can act in a similar way to a human neuron. Made from hydrogel, the artificial neurons are about 0.7 millimetres across ­– about 700 times wider than a human neuron, but similar to giant axons found in squid. They can also be made up to 25 millimetres long, which is similar in length to a human optic nerve running from the eye to the brain.
When a light is shone on the synthetic neuron, it activates proteins that pump hydrogen ions into the cell. These positively charged ions then move through the neuron, carrying an electrical signal. The speed of transmission was too fast to measure with the team’s equipment and is probably faster than the rate in natural neurons, says Bayley. When the positive charge reaches the tip of the neuron, it makes adenosine triphosphate (ATP) – a neurotransmitter chemicalmove from one water droplet to another. In future work, the researchers hope to make the synthetic neuron interact with another via an ATP signal, just as neurons connect with each other at synapses.
The team bundled seven of the neurons together to work in parallel as a synthetic nerve. “This allows us to send multiple signals simultaneously,” says Bayley. “They can all have very different frequencies and so it’s a very versatile signal.” The main purpose is to send different pieces of information down the same pathway, he says.

Artificial nerve cells made from biocompatible materials have been made in a lab for the first time. The innovation may one day be used in synthetic tissues to repair organs such as the heart or the eyes. 

However, the artificial neurons still have a long way to go. Unlike real neurons, there is no mechanism to recycle and create new neurotransmitters in the synthetic system. The neurons therefore only work for a few hours, says Bayley. “The more you do science, the more you find out how clever science is by virtue of evolution.” Alain Nogaret at the University of Bath in the UK says the innovation could play a major role in improving neuro-implants such as artificial retinas by the end of the decade. “The emulation of nervous activity in soft materials is a major step towards non-invasive brain-machine interfaces and solutions addressing neurodegenerative disease.”

Bayley hopes to eventually use these synthetic neurons to deliver different types of drugs simultaneously to treat wounds more quickly and precisely. “Using light, we could maybe release drug molecules in a patterned way,” he says.
Source: https://www.nature.com/ 
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https://www.scientiststudy.com/

Human Retinas Grown In A Dish

Biologists at Johns Hopkins University grew human retinas from scratch to determine how cells that allow people to see in color are made. The work, set for publication in the journal Science, lays the foundation to develop therapies for eye diseases such as color blindness and macular degeneration. It also establishes lab-created “organoids” as a model to study human development on a cellular level.

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Everything we examine looks like a normal developing eye, just growing in a dish,” said Robert Johnston, a developmental biologist at Johns Hopkins. “You have a model system that you can manipulate without studying humans directly.” Johnston’s lab explores how a cell’s fate is determined—or what happens in the womb to turn a developing cell into a specific type of cell, an aspect of human biology that is largely unknown. Here, he and his team focused on the cells that allow people to see blue, red and green—the three cone photoreceptors in the human eye.

While most vision research is done on mice and fish, neither of those species has the dynamic daytime and color vision of humans. So Johnston’s team created the human eye tissue they needed—with stem cells. “Trichromatic color vision differentiates us from most other mammals,” said lead author Kiara Eldred, a Johns Hopkins graduate student. “Our research is really trying to figure out what pathways these cells take to give us that special color vision.”

Source: https://hub.jhu.edu/