Front page of science magazine New Scientist, a hand prunes a bonsai tree. But we’re not talking about gardening here. The title sheds light on the metaphor of drawing: in laboratories, “we grow human brains”.
To the naked eye, they look like amorphous blobs, is chasing the British title. But through a powerful microscope “appears all their inner complexity”. The magazine’s dossier is thus devoted to the culture of “cerebral organoids”, also called “mini-brains”, a dozen of which grow in the laboratory of Madeline Lancaster at the University of Cambridge.
The scientist was the first to install these brains in gel to add dimension to them, in 2013, rather than flat, as other researchers had used to study them since 2006. “In 2013, Madeline Lancaster recounted how, after two months, brain-like lobes of tissue had grown out of her organoids.
These minibrains “are sources of immense hope for a better understanding of the brain”, pursues the English title. For now, they have already served to understand “how it is different in autistic people and how it begins to malfunction in the event of dementia or motor neuron diseases (cell specialized in controlling movements via a nervous impulse system), for example”.
Similar most “not quite the same”
To fully exploit the scientific potential of these organoids, neuroscientists aim to create larger and more complex ones – some are already trying to grow them with blood vessels.
“For the development of organoids, the discovery of stem cells, which can more easily multiply and be manipulated in a cup than ordinary body cells, has been instrumental.”
These mini-brains produce electrical signals known as brain waves, “of a complexity equivalent to that of a fetus approximately one month before birth”, developed New Scientist. After nine months, they evolve into a complexity resembling that of a prenatal human brain.
But the title to relativize: “That’s not to say that minibrains are identical to the brain of a real fetus or baby, especially since you can’t make them larger than a few millimeters in diameter.” Rather, the goal is to understand the evolution and development of the human organ. To try to answer the question, summarizes Madeline Lancaster, of “what makes the specificity of human beings as a species”.