Human brains Grown in Petri Dish

Mini brain: An organoid derived from stem cells contains different brain regions. Green shows neurons and pink/red shows neuronal stem cells.

Scientists at the Institute of Molecular Biotechnology in Vienna, Austria, have grown three-dimensional human brain tissues from stem cells. The tissues form discrete structures that are seen in the developing brain.

The Vienna researchers found that immature brain cells derived from stem cells self-organize into brain-like tissues in the right culture conditions. The “cerebral organoids, ” as the researchers call them, grew to about four millimeters in size and could survive as long as 10 months. For decades, scientists have been able to take cells from animals including humans and grow them in a petri dish, but for the most part this has been done in two dimensions, with the cells grown in a thin layer in petri dishes. But in recent years, researchers have advanced tissue culture techniques so that three-dimensional brain tissue can grow in the lab. The new report from the Austrian team demonstrates that allowing immature brain cells to self-organize yields some of the largest and most complex lab-grown brain tissue, with distinct subregions and signs of functional neurons.

The work, published in Nature on Wednesday, is the latest advance in a field focused on creating more lifelike tissue cultures of neurons and related cells for studying brain function, disease, and repair. With a cultured cell model system that mimics the brain’s natural architecture, researchers would be able to look at how certain diseases occur and screen potential medications for toxicity and efficacy in a more natural setting, says Anja Kunze, a neuroengineer at the University of California, Los Angeles, who has developed three-dimensional brain tissue cultures to study Alzheimer’s disease.

The Austrian researchers coaxed cultured neurons to take on a three-dimensional organization using cell-friendly scaffolding materials in the cultures. The team also let the neuron progenitors control their own fate. “Stem cells have an amazing ability to self-organize, ” said study first author Madeline Lancaster at a press briefing on Tuesday. Others groups have also recently seen success in allowing progenitor cells to self-organize, leading to reports of primitive eye structures, liver buds, and more (see “Growing Eyeballs” and “A Rudimentary Liver Is Grown from Stem Cells”).

The brain tissue formed discrete regions found in the early developing human brain, including regions that resemble parts of the cortex, the retina, and structures that produce cerebrospinal fluid. At the press briefing, senior author Juergen Knoblich said that while there have been numerous attempts to model human brain tissue in a culture using human cells, the complex human organ has proved difficult to replicate. Knoblich says the proto-brain resembles the developmental stage of a nine-week-old fetus’s brain.