Scientists ‘create’ a tiny brain

For the first time, scientists have grown a brain in a dish.

In a study published in the journal Nature last month, Austrian researchers used human induced pluripotent stem cells or embryonic stem cells and a combination of specialized growth conditions to produce “cerebral organoids.”

Within these organoids, the authors can define many, but not all, of the discrete brain regions found in the human brain. The organization of these regions in relation to one another is not the same as in a human brain, and the connectivity between brain regions is not intact. Nonetheless, some of these regions, including the cerebral cortex, are internally organized exactly as they would be in the human brain. The organoids are developmentally similar to a 9-week old embryo (about the size of a pea), making them a great model for studying early human brain development.

The authors used these miniature brains to make a new discovery about the molecular basis of a disease called microcephaly, where brain size is severely reduced. This disease has been difficult to study using animal models, because the brain regions that malfunction in the human disease don’t exist in many other animals. Importantly, the researchers used induced pluripotent stem cells isolated from the skin of human patients with microcephaly to grow the diseased organoids. Modeling the disease in this way, the researchers come as close as possible to a tailored view of the malfunction that occurred in these same patients during brain development in utero.

The authors do emphasize that it is impossible to grow an entire human brain in a dish — so we are a far cry from Mary Shelley’s Frankenstein. But there is no doubt that cerebral organoids will be a great tool to study many of the complicated pathways that converge for early development of the human brain to proceed properly. By studying these processes in a dish in the lab, scientists have the benefit of examining development in real-time, instead of relying on snap shots from tissue isolated during different developmental time points. Researchers can also manipulate the growth and nutrient environments of the organoids, as well as perform genetic manipulations and drug treatments to tease apart different aspects of brain development. Future studies using these miniature brains may even pave the way for new therapeutic treatments for some developmental diseases.

Kateri Spinelli, Ph.D.
Post doctoral fellow, Dept. of Neurology
OHSU Brain Institute