With the right mix of nutrients and a little bit of coaxing, human stem cells derived from skin can assemble spontaneously into brain-like chunks of tissue. Researchers provide the first description and application of these ‘mini-brains’ today in Nature1. “It’s a seminal study to making a brain in a dish,” says Clive Svendsen, a neurobiologist at the University of California, Los Angeles, who was not involved in the study. “That’s phenomenal.” A fully formed artificial brain might still be years away, he notes, but the pea-sized neural clumps developed in this work could prove useful for researching human neurological diseases. Researchers have previously used human stem cells to grow structures resembling the eye2 and even tissue layers similar to the brain's cortex3. But in the latest advance, scientists developed bigger and more complex neural-tissue clumps by first growing the stem cells on a synthetic gel that resembled natural connective tissues found in the brain and elsewhere in the body. Then, they plopped the nascent clumps into a spinning bath to infuse the tissue with nutrients and oxygen.
“The big surprise was that it worked,” says study co-author Juergen Knoblich, a developmental biologist at the Institute of Molecular Biotechnology in Vienna. The blobs grew to resemble the brains of fetuses in the ninth week of development. Under a microscope, researchers saw discrete brain regions that seemed to interact with one another. But the overall arrangement of the different proto-brain areas varied randomly across tissue samples — amounting to no recognizable physiological structure.