Model Mini Brains

You don’t need to be a neuroscientist to notice the size and structural differences between these two brain organoids – cultured clumps of brain cells that replicate certain features and functions of actual brain tissue. These 'mini-brains' were generated from human stem cells and differ because of the donors. Cells from a person with Pitt-Hopkins syndrome – a severe form of autism spectrum disorder characterised by intellectual disability, developmental delay and seizures – were used to generate the organoid on the right, while cells from someone without the condition generated the one on the left. Mutations to a gene called TCF4 cause Pitt-Hopkins syndrome and studying the patient-derived organoids revealed how the mutation impairs proper growth and development of neurons. Encouragingly, mutation-fixing gene therapy performed on the mini-brains improved the cells’ development and function, providing hope that similar therapies might one day alleviate symptoms in children with this rare but debilitating condition.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image from work by Fabio Papes and Alysson R. Muotri, and colleagues, UC San Diego Health Sciences
• Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA, USA
• Image copyright held by the original authors
• Research published in Nature Communications, May 2022