It might be the tiniest EEG electrode cap ever made, designed to monitor activity in a tiny, pen-dot-sized brain model. The device’s creators hope it will advance knowledge of neurological problems and the effects of potentially harmful chemicals on the brain.
This engineering achievement, led by researchers from Johns Hopkins University and reported today in Science Advances, broadens the range of tasks that can be carried out using organoids, such as mini brains, which are lab-grown spheres of human cells that closely resemble the structure and functionality of the brain.
Since the development of organoids more than ten years ago, scientists have altered stem cells to produce miniature kidneys, lungs, livers, and brains. The intricate, small models are utilised to research the development of the organs.
Organoids that have been genetically altered, virally injected, or exposed to chemicals are studied alongside organoids that have not undergone these changes.
Because organoids, especially tiny brains, may be employed in investigations that would otherwise need testing on humans or animals, they are becoming more and more significant in medical research.
But because the typical testing equipment for organoids is flat, researchers have only been able to look at a small number of the cells on their surface.
According to Gracias, understanding what is occurring to a larger number of cells in the organoid would improve in understanding how organs work and how diseases develop.
The researchers developed miniature EEG caps for brain organoids from self-folding polymer leaflets with conductive polymer-coated metal electrodes, drawing inspiration from the electrode-dotted skull caps used to identify brain malignancies.
The microcaps completely encircle an organoid’s spherical shape, enabling 3D recording from the entire surface, allowing researchers to, among other things, listen to neurons’ spontaneous electrical communication while subjecting them to drugs.
The information should outperform current readings from standard electrodes on a flat plate.
According to co-author Thomas Hartung, director of the Center for Alternatives to Animal Testing at Johns Hopkins Bloomberg School of Public Health, with more precise information from organoids, researchers can investigate whether chemicals used in consumer products cause issues with brain development.
Readings from the caps might potentially cut down on the number of animals needed to evaluate chemical effects, according to researchers. Traditionally, it costs and involves 1,000 rats to evaluate a single chemical.
According to Hartung, conventional testing for just one chemical needs roughly 1,000 rats and costs about $1 million. He continued that although human brains are quite dissimilar from rat and mouse brains, the findings from organoids are also more applicable.
Johns Hopkins University
Huang, Q., et al. (2022) Shell microelectrode arrays (MEAs) for brain organoids. Science Advances. doi.org/10.1126/sciadv.abq5031.