Scientists find cheap, easy way to make ‘mini brains’

Researchers have developed an easy and less expensive method to produce 3D miniature brains that can be used for drug testing, to test neural tissue transplants, or to experiment with how stem cells work.

Although the mini brains are not capable of thinking, they produce electrical signals and form their own neural connections - synapses - making them readily producible testbeds for neuroscience research, scientists said.

"We think of this as a way to have a better in vitro (lab) model that can maybe reduce animal use," said co-lead author Molly Boutin, graduate student at Brown University in the US.

"A lot of the work that's done right now is in two-dimensional culture, but this is an alternative that is much more relevant to the in vivo (living) scenario," Boutin said.

Just a small sample of living tissue from a single rodent can make thousands of mini-brains, the researchers said.

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 millimetre 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 materials are easy to get and the mini-brains are simple to make," said co-lead author Yu-Ting Dingle, who was doing her PhD at Brown University during the research.

She compared them to retail 3D printers, which have proliferated in recent years, bringing that once-rare technology to more of a mass market.

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

"There are fixed costs, of course, but an approximate cost for each new mini-brain is on the order of USD 0.25," said senior author Diane Hoffman-Kim, associate professor at Brown University.

The new method yielded mini-brains with several important properties. The brains were electrically active, the neurons fire and spike and form synaptic connections, producing complex networks.

Experiments showed that the mini-brains have a density of a few hundred thousand cells per cubic millimetre, which is similar to a natural rodent brain.

The study was published in the journal Tissue Engineering: Part C.