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Why two brains are better than one

Mar 31,2018




A radical technique that makes mature cells act like stem cells is growing a mini brain from tissue I donated. One day it could produce whole organs for transplant.

Last week, I was told my other brain is fully grown. It doesn’t look like much. A blob of pale flesh about the size of a small pea, it floats in a bath of blood-red nutrient. It would fit into the cranium of a foetus barely a month old. Still, it’s a “brain” after a fashion and it’s made from me. From a piece of my arm, to be precise. I’m not going to pretend this isn’t strange. But neither is it an exercise in gratuitously ghoulish biological engineering, a piece of Frankensteinian scientific hubris 200 years after Mary Shelley’s tale. The researchers who made my mini-brain are trying to understand how neurodegenerative diseases develop. With mini-brains grown from the tissues of people who have a genetic susceptibility to the early onset of conditions such as Alzheimer’s, they hope to unravel what goes awry in the mature adult brain. It’s this link to studies of dementia that led me to the little room in the Dementia Research Centre of University College London last July, where neuroscientist Ross Paterson anaesthetised my upper arm and then sliced a small plug of flesh from it. This biopsy was going to be the seed for growing brain cells – neurons – that would organise themselves into mini-brains.

The Brains in a Dish project is one of many strands of Created Out of Mind, an initiative hosted at the Wellcome Collection in London and funded by the Wellcome Trust for two years to explore, challenge and shape perceptions and understanding of dementias through science and the creative arts. Neuroscientist Selina Wray at UCL is studying the genetics of Alzheimer’s and other neurodegenerative diseases and she and her PhD student Christopher Lovejoy gamely agreed to culture mini-brains from cells taken from four of the Created Out of Mind team: artist Charlie Murphy, who is leading Brains in a Dish, BBC journalist Fergus Walsh, neurologist Nick Fox and me. It was a no-brainer… well, you know what I mean. Who could resist the narcissistic flattery of having another brain grown for them? I was curious how it would feel. Would I see this piece of disembodied tissue as truly mine? Would I feel protective of, even concerned for, a tiny “organoid” floating in a petri dish? Most of all, I was attracted by the extraordinary scientific feat of turning a lump of arm into something like a brain.

There’s a lot of baggage in that “something like”. Some researchers dislike the term “mini-brain” and with reason. This pea-size object is not a miniature version of the brain in my skull. It’s not even quite like the immature developing brain of an early-stage foetus. Without a body, neurons don’t quite know how to make a proper brain. But neither are mini-brains blobs of identical neurons, like, say, a small chunk of my cortex. One can fairly say that the neurons “want” to make a brain but, lacking proper guidance, don’t quite know how to go about it. So they make a reasonable but imperfect approximation. The mini-brain contains several types of brain cell, arranged somewhat as in a real brain – in layers such as those of the cortex, for example. The mini-brain even contains sketchy little versions of the folds and grooves on the surface of a true brain and appendages that, in a foetal brain, would become the brain stem and central nervous system, extending down the spine. What’s most astonishing about this project is that these neurons started out as a piece of my arm. Those skin-forming cells, fibroblasts, were turned into brain cells using a technique discovered barely 10 years ago and that has revolutionised tissue engineering and embryo research and won its creator, Shinya Yamanaka, a Nobel prize. It also overturned decades of conventional wisdom in cell biology.