Neuroscientists in the US have successfully adapted mice to have functioning human cells inside their brains. This breakthrough could allow for the testing of potential treatments for psychiatric and neurodevelopmental diseases that are unique to humans.
The Stanford University researchers genetically engineered mice to develop almost none of their own cerebral cortex, the outer layer of the brain responsible for higher-level thinking. They then reprogrammed human skin cells to grow into brain-like tissue, known as organoids, which were implanted into the mouse brains.
These human cells divided and organised themselves within the animals' existing brain circuitry, connecting with the mouse's brain and spinal cord. After several months, the human cells began to function similarly to the outer layer of the mouse's brain.
Lead researcher Professor Sergiu Pașca stated that this new model allows for the capture of aspects of human brain function previously not possible. The work, published in the journal Nature, was carried out with independent ethical scrutiny.