‘Brain on a chip’ reveals how the brain folds
Being born with a “tabula rasa” – a clean slate – is, in the case of the brain, something of a curse. Our brains are already wrinkled like walnuts by the time we are born. Babies born without these wrinkles – called smooth brain syndrome – suffer from severe developmental deficiencies and their life expectancy is markedly reduced. The gene that causes this syndrome recently helped Weizmann Institute of Science researchers to probe the physical forces that cause the brain’s wrinkles to form. In their findings, reported in Nature Physics, the researchers describe a method they developed for growing tiny “brains on chips” from human cells that enabled them to track the physical and biological mechanisms underlying the wrinkling process.
Tiny brains grown in the lab from embryonic stem cells – so-called organoids – were pioneered in the last decade by Profs. Yoshiki Sasai in Japan and Juergen Knoblich in Austria. Prof. Orly Reiner of the Institute’s Department of Molecular Genetics says that her lab, along with many others, embraced the idea of growing organoids. But Dr. Eyal Karzbrun, a member of the Reiner Lab, had to put a bit of a damper on their enthusiasm: the sizes of the organoids they obtained were far from uniform; with no blood vessels, the insides did not have a steady supply of nutrients and started to die; and the thickness of the tissue got in the way of the optical imaging and microscope tracking.
