From BBC News · · 2m
Scientists grow human brain cells inside mice
Researchers implanted human brain tissue into mice to test treatments for disorders that don't occur in rodents.
In brief
Researchers implanted human brain tissue into mice to test treatments for disorders that don't occur in rodents. Human brain cells can integrate into mouse brains, offering a new way to study human neurological disorders, but raises ethical questions about animal cognition. Originally reported by BBC News.
Human brain cells now grow in mice
US neuroscientists successfully implanted human brain tissue into mice, creating animals with partly human brains. The goal is to test treatments for psychiatric and neurological diseases that only affect humans.
Why mice need human brains
Many brain disorders like autism and epilepsy don't naturally occur in mice, making them poor models for testing treatments. Current psychiatric drugs often fail in human trials even after succeeding in animal tests.
“Even drugs that actually make it to clinical trial - that seem to be working really well in animal models - fail dramatically in clinic.”
How they built the hybrid brains
Researchers genetically engineered mice to lack most of their cerebral cortex, then implanted human brain tissue grown from reprogrammed skin cells. The human cells integrated into the mouse brain's existing circuits.
The mice behave normally
After six months, the implanted mice performed standard behavioral tests just like normal mice. The human cells didn't enhance the animals' abilities or change how they think.
“They don't have any enhancement.”
Human brain cells spontaneously organized
Cell types found only in human and primate brains formed naturally in the implanted mice. This suggests the human tissue retained its biological programming even in a mouse environment.
“You're keeping the human program inside the mouse environment, like the mouse is an incubator.”
Major ethical questions emerge
Bioethicists worry about what it means to alter animal cognition and whether we can know what these mice experience. The research was conducted with independent ethical oversight.
“How can we know what it's like to be one of these mice?”
Limited practical use for now
These mice will likely be used only in a few labs to study specific brain disorders. The ethical concerns about raising human brain tissue in animals may limit their broader application.
A new avenue for brain research
Scientists studying human brain disease have limited options: mice, cells in dishes, or computer models. This hybrid approach offers a new way to understand human neurological conditions.
The short version
Human brain cells can integrate into mouse brains, offering a new way to study human neurological disorders, but raises ethical questions about animal cognition.
