Roughly 60% of the 12 million animal experiments in Europe each year involve mice. But despite their undoubted usefulness, mice haven’t been much help in getting successful drugs into patients with brain conditions such as autism, schizophrenia or Alzheimer’s disease. So too have researchers grown 2D human brain cells in a dish. However, human brain tissue comprises many cell types in complex 3D arrangements, necessary for true cell identity and function to emerge.

Researchers are hopeful that lab grown mini-brains – tiny 3D tissues resembling the early human brain – may offer a more promising approach. ‘We first published on them in 2013, but the number of brain organoid papers has since skyrocketed, with 300 just last year,’ says Madeline Lancaster at the Medical Research Council’s Laboratory of Molecular Biology lab in Cambridge, UK.

 pippette and petri dish

Lancaster was the first to grow mini-brains – or brain organoids – as a postdoc in the lab of Juergen Knoblich at the Institute of Molecular Biotechnology in Vienna, Austria. The miniature brains comprised parts of the cortex, hippocampus and even retinas, resembling a jumbled-up brain of a human foetus.

‘We were stunned by how similar the events in the organoids were to what happens in a human embryo,’ says Knoblich. To be clear, the brain tissue is not a downsized replicate. Lancaster compares the blobs of tissue to an aircraft disassembled and put back together, with the engine, cockpit and wings in the wrong place.

Growing mini brains to discover what makes us human | Madeline Lancaster. Video: TEDx Talks  

‘The plane wouldn’t fly, but you can study each of those components and learn about them. This is the same with brain organoids. They develop features similar to the human brain,’ she explains.