Rat gets human brain cells in first-of-kind implant surgery

Human brain cells were successfully implanted into newborn rats for the first time, paving the way to study complex psychiatric disorders, such as autism and schizophrenia and test treatments.

Studying how these conditions develop is incredibly difficult — animals do not experience them like people, and humans cannot simply be opened up for research, Daily Sabah report.

Scientists can assemble small sections of human brain tissue derived from stem cells in petri dishes and have already done so with more than a dozen brain regions.

But in dishes, "neurons don't grow to the size which a human neuron in an actual human brain would grow," said Sergiu Pasca, the study's lead author and professor of psychiatry and behavioural sciences at Stanford University.

And isolated from a body, they cannot tell us what symptoms a defect will cause.

To overcome those limitations, researchers implanted the groupings of human brain cells, called organoids, into the brains of young rats.

The rats' age was important: Human neurons have been implanted into adult rats before, but an animal's brain stops developing at a certain age, limiting how well-implanted cells can integrate.

"By transplanting them at these early stages, we found that these organoids can grow relatively large, they become vascularised (receive nutrients) by the rat, and they can cover about a third of a rat's (brain) hemisphere," Pasca said.