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Scientists Create Mice with Half Human Brain, Restoring Cognition
Confirmed
In Short: In a groundbreaking study, scientists implanted human brain organoids into mice missing half their brain, restoring their cognitive functions.
Scientists have successfully implanted human brain organoids into mice that are missing half their brain, according to a study published in Nature. The researchers, led by Sergiu Pașca at Stanford University, genetically engineered mice to lack more than 90 percent of their cortex, or about half their brain. These mice, called XCX mice, were then transplanted with tiny versions of the human cerebral cortex, a region involved in memory, movement, and thinking.
Not only did the organoids integrate into the mice's brains, but they also restored most of their cognitive functions. The mice performed better in a memory test, where they had to navigate a maze, compared to a control group of normal mice. 'The mouse is relatively sick without a cortex, then you transplant these organoids in, and it behaves more like the normal mouse,' says Gabriel Balmuș, a researcher at the University of Cambridge who was not involved in the study.
The study also revealed that the organoids had grown to form cortex-like grafts, filling the cavity in each of the mice's skulls. Scans showed that the organoids had integrated into the mice's brains, restoring their cognitive functions. 'Half the volume of the brain is initially gone, and now largely 90 percent of that missing volume is covered by human cells,' said Pașca.
According to Pașca, these studies only showed that such organoids can alter cognition, rather than improve it. However, the findings suggest that human brain organoids could potentially be used to study brain disorders and develop new treatments. 'These mice only experience some memory and movement deficits, since their brain adapts to compensate for their missing cortex,' says Pașca.
The research also highlights the potential of using human brain organoids to better understand what truly makes humans unique. In another experiment, the team showed that human organoid transplants made mice respond to hypoxia, or low oxygen levels, in a similar way to people. This suggests that the organoids can mimic human brain responses to environmental changes.
What's confirmed
- Scientists have successfully implanted human brain organoids into mice that are missing half their brain, according to a study published in Nature. The researchers, led by Sergiu Pașca at Stanford University, genetically engineered mice to lack more than 90 percent of their cortex, or about half their brain. These mice, called XCX mice, were then transplanted with tiny versions of the human cerebral cortex, a region involved in memory, movement, and thinking.
- Not only did the organoids integrate into the mice's brains, but they also restored most of their cognitive functions. The mice performed better in a memory test, where they had to navigate a maze, compared to a control group of normal mice. 'The mouse is relatively sick without a cortex, then you transplant these organoids in, and it behaves more like the normal mouse,' says Gabriel Balmuș, a researcher at the University of Cambridge who was not involved in the study.
- The study also revealed that the organoids had grown to form cortex-like grafts, filling the cavity in each of the mice's skulls. Scans showed that the organoids had integrated into the mice's brains, restoring their cognitive functions. 'Half the volume of the brain is initially gone, and now largely 90 percent of that missing volume is covered by human cells,' said Pașca.
- According to Pașca, these studies only showed that such organoids can alter cognition, rather than improve it. However, the findings suggest that human brain organoids could potentially be used to study brain disorders and develop new treatments. 'These mice only experience some memory and movement deficits, since their brain adapts to compensate for their missing cortex,' says Pașca.
- The research also highlights the potential of using human brain organoids to better understand what truly makes humans unique. In another experiment, the team showed that human organoid transplants made mice respond to hypoxia, or low oxygen levels, in a similar way to people. This suggests that the organoids can mimic human brain responses to environmental changes.
What's still developing
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- The remaining mice, apallial mice, didn’t receive the transplants.
- But this deficit was almost completely reversed in the XCX mice.
- In a study published Wednesday in Nature, the Stanford team reported finding types of human cells inside the brains of 3-month-old chimeric mouse pups that are very hard to obtain in a dish.