A bioengineering team at Brown University can grow "mini-brains" of neurons and supporting cells that form networks and are electrically active. The advance could provide an inexpensive and easy-to-make 3-D testbed for biomedical research. The little balls of brain aren't performing any cogitation, but they produce electrical signals and form their own neural connections: synapses, making them readily producible testbeds for neuroscience research.

Just a small sample of living tissue from a single rodent can make thousands of mini-brain. “The recipe” involves isolating and concentrating the desired cells with some centrifuge steps and using that refined sample to seed the cell culture in medium in an agarose spherical mold.

The mini-brains, about a third of a millimeter in diameter, are not the first or the most sophisticated working cell cultures of a central nervous system, the researchers acknowledged, but they require fewer steps to make and they use more readily available materials.

The spheres of brain tissue begin to form within a day after the cultures are seeded and have formed complex 3-D neural networks within two to three weeks.

The method they developed yields mini-brains with several important properties:

  • Diverse cell types: The cultures contain both inhibitory and excitatory neurons and several varieties of essential neural support cells called glia.
  • Electrically active: the neurons fire and spike and form synaptic connections, producing complex networks.
  • 3-D: Cells connect and communicate within a realistic geometry, rather than merely across a flat plane as in a 2-D culture.
  • Natural density: Experiments showed that the mini-brains have a density of a few hundred thousand cells per cubic millimeter, which is similar to a natural rodent brain.
  • Physical structure: Cells in the mini-brain produce their own extracellular matrix, producing a tissue with the same mechanical properties (squishiness) as natural tissue. The cultures also don't rely on foreign materials such as scaffolds of collagen.
  • Longevity: In testing, cultured tissues live for at least a month.

One of the major problems in understanding mental disorders is that we can’t directly access the human brain. These spheroids closely resemble the three-dimensional architecture of the cortex and have gene-expression patterns that mimic those in a developing fetal brain.

Scientists hope that these tiny free-floating “brains” will help further our knowledge of how the nervous system develops and allow researchers to pick apart the mechanisms contributing to certain neuropsychiatric diseases, such as autism and schizophrenia.

References:

  • http://www.iflscience.com/brain/scientists-grow-mini-brains-patient-skin-cells
  • http://www.sciencedaily.com/releases/2015/10/151001093854.htm
  • https://news.brown.edu/articles/2015/10/minibrain
  • Image adapted from: http://medicalxpress.com/news/2015-10-accessible-approach-mini-brain.html

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