Human brain cells transplanted onto rat brain can influence its behavior, Stanford study suggests

They believe the data could provide critical insight into forms of autism and perhaps many other psychiatric disorders.

ByJobina Fortson via KGO logo
Friday, October 14, 2022
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Stanford scientists are exploring new ways to study conditions like autism and ADHD by transplanting human brain cells onto the brain of a living rat.

STANFORD, Calif. -- For decades researchers have been peering into the human brain, trying to unlock the secrets of conditions ranging from autism to epilepsy to mental illness.

But now, instead of just looking at the brain, a team at Stanford says they've built their own or at least a tiny part of one. The trick is that the brain cells, known as organoids, don't live in a human's head - they live in a rat's.

"And so we've done this by transplanting the organoids, early in the developing rat. So at a time where, when the rat brain is still plastic, and can still form new connections," says Sergiu Pasca, MD, a professor psychiatry and behavioral sciences at the Stanford School of Medicine.

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He says the first step was to create the brain tissue using what are known as pluripotent stem cells. They're derived from skin samples, and can be coaxed into developing into almost any kind of cell in the body. But instead of just working in a dish, Pasca's team transplanted the cells onto the brain of a living rat. They soon watched as blood vessels connected, and the human neurons began to grow.

"And we've discovered that it starts to connect with the, with the some of the circuitry of the rat. And so for instance, it receives input from the thalamus, which is a very important structure in the middle of the brain, which relays information from sensors. So because we put it in the region of the brain that processes information from whiskers," explains prof. Pasca.

Researchers were able to confirm that sensations from the rat's whiskers were being processed by the human brain cells. Later they engineered cells that were sensitive to a colored light, then taught the rat to associate the light with a reward. Behavior, again being processed through the human brain cells.

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The Stanford team is clear that they are not working to create a humanized rat. But instead, to develop a platform to research diseases, drugs, and therapies on living brain tissue in a way that could never be done with human patients.

They believe the data could provide critical insight into forms of autism and perhaps many other conditions, including psychiatric disorders.

"I mean, neuropsychiatric disorders are the largest cause of disability, they pose an immense burden to society, or overall. And we've, you know, we've made little progress in understanding the biology of this condition is primarily because the human brain is inaccessible," says prof. Pasca.

But with this new access, they're hoping faster testing will lead to new drugs, and perhaps a powerful new way of studying the human brain.